The FBI is investigating possible links between US President Donald Trump's election team and the Russian government, Director James Comey told the House Intelligence Committee on Monday.

The intelligence agency is investigating Russian government interference in the US election and any links or cooperation between the Trump campaign team and Moscow, Comey told the panel, taking the unusual step of confirming an ongoing investigation.

The investigation is classified and Comey said he would not reveal more about the investigation or whom it is investigating.

Congressman Devin Nunes, a California Republican and chairman of the committee, said the panel aimed to get to the bottom of Russian actions and whether anyone from a political campaign conspired with them.

He also said the panel would look at allegations of "improper surveillance" after Trump charged that former president Barack Obama had order the wiretapping of his offices.

Nunes said lawmakers "know there was not a physical wiretap of Trump Tower," but said it was possible that other techniques were used against Trump and his associates.

Comey confirmed there was "no information" to support Trump's claims that the FBI wiretapped his offices.

"I have no information that supports those tweets and we have looked carefully inside the FBI," he said. "The Department of Justice has asked me to share that the information is the same for the department and all its components."

Comey said it was outside the power of the president to order a wiretapping of any US citizen.

In a more than five-hour hearing, Republicans on the committee focused on the damage caused by intelligence leaks, while Democrats focused on the Trump-Russia ties.

Nunes urged Comey to conduct a quick investigation because it was casting "a big, gray cloud that you've put over people who have very important work to do leading this country."

The White House however stood its ground, insisting there was no evidence Trump's team colluded with the Russians and that the president would still not withdraw allegations that Obama had ordered him to be surveilled.

"Investigating it and having proof of it are two different things," spokesman Sean Spicer said, noting the ongoing hearing in Congress was just the first of many.

Using his official government Twitter account, Trump had tweeted selective video clips from the hearing, claiming they showed "Russia did not influence the electoral process."

Comey however was asked about the reading during the hearing and declared it to be a misreading of his comments.

Trump had earlier weighed in before the hearing got underway to deny Russian meddling in the 2016 US elections.

"The Democrats made up and pushed the Russian story as an excuse for running a terrible campaign," Trump wrote on Twitter.

US intelligence agencies last year declared that hacking against Democratic Party organizations, which led to leaks of embarrassing information about the left-leaning party and its presidential nominee, Hillary Clinton, was likely directed by the highest levels of the Russian government.

Admiral Mike Rogers, head of the National Security Agency, told the panel that the intelligence community stands by that assessment.

The furore about the claims has mushroomed in recent months, with allegations that Russian officials held sway over Trump's campaign dogging his young administration for weeks now.

Those charges have proven hard to shake, given that Trump's first national security advisor, Michael Flynn, resigned after it emerged that he lied about contact with Russian officials before entering office.

Similarly, US Attorney General Jeff Sessions has been accused of lying about meetings with Russian officials.

But Trump, in his tweets, stood firm, noting that former director of national intelligence James Clapper said during a televised interview Sunday that he was not aware of any evidence linking Trump or his team to Russia.

"James Clapper and others stated that there is no evidence Potus colluded with Russia. This story is FAKE NEWS and everyone knows it!" tweeted Trump.

The president argued instead that the true problem is that so much information about the inner workings of his administration are being leaked to the media.

"The real story that Congress, the FBI and all others should be looking into is the leaking of classified information. Must find leaker now!" he tweeted.

As president, Trump has the authority to direct the FBI to launch such a probe.

Latest news

Syrian opposition rules out future role for President al-Assad

The Syrian opposition said Friday it would not accept any role for President Bashar al-Assad in the future of the war-torn country, reacting to a recent US shift saying that removing al-Assad is no longer a priority for Washington.

Russian Army integrates breakaway forces of Georgian province

Parts of the small fighting forces of the Georgian breakaway province of South Ossetia have been placed under Russian military control, Russian Defence Minister Sergei Shoigu said on Friday.

Czech Republic's Pilsner Urquell beer is now Japanese

Japanese brewing company Asahi completed its takeover of the Czech brewery Pilsner Urquell on Friday, Asahi said in a statement.

Judge approves 25-million-dollar settlement of Trump University case

A US district judge on Friday approved a 25-million-dollar settlement of lawsuits and state fraud allegations against Trump University, the US president's now-defunct business venture.

Former Thai premier Thaksin to junta on reconciliation: 'Cut me out'

Former Thai prime minister Thaksin Shinawatra on Friday announced that he is not interested in the junta-led reconciliation process, three days after the junta handed him a half-a-billion-dollar tax bill for his past business deal.

Dalic: We welcome possible deal between Agrokor and banks

The government welcomes the possibility of an agreement being concluded between the Agrokor food company and creditor banks, and the bill on vitally important companies is not a fallback plan but the result of the government's care for the overall economic and financial stability of Croatia, Deputy Prime Minister and Minister of Economy Martina Dalic told a press conference in Zagreb on Friday.

Croatia, China sign action plan for cooperation in agriculture

The Croatian and Chinese ministries of agriculture on Friday signed an action plan for cooperation in the field of agriculture for the period 2017-2018, the Croatian ministry said in a statement.

ZSE indices up, Agrokor shares in focus of investor interest

The Zagreb Stock Exchange (ZSE) indices on Friday rose by more than 1.8%, with stocks of the Agrokor food and retail concern being in the focus of investor interest again.

Berlin police defend handling of Berlin market attacker

Berlin police defended themselves on Friday against accusations that they stopped surveillance on Berlin Christmas market attacker despite knowing in June 2016 he was dangerous.

Croatia, creditors tailor emergency measures to save tottering giant

Croatia's tottering retail and food giant Agrokor reached an agreement with its creditors, putting its debts standby and allowing it to continue working during emergency restructuring, the Croatian branch of Austria's Erste Bank said Friday.

Agrokor's creditors say standstill agreement to go into force today

A standstill agreement regarding the Agrokor concern's existing financial obligations to banks will take effect on Friday, additional capital will be injected into the concern in the coming days and the concern will be actively restructured, which includes a change of its management, it was said on Friday after a meeting between Agrokor's suppliers and creditor banks.

Palestinians, UN slam Israel's new settlement plan

Palestinians, Israeli activists and the UN lambasted the government of Israeli Prime Minister Benjamin Netanyahu on Friday, a day after it gave the go-ahead for the first new West Bank settlement in a quarter of a century.

South Sudan rebels release three abducted foreign oil workers

South Sudanese rebels have released three foreign engineers they abducted in early March in the oil-rich Upper Nile region, Foreign Affairs Ministry official Mawein Makol Arik said on Friday.

Turkish opposition: Imprisoned party chief has gone on hunger strike

The head of Turkey's pro-Kurdish opposition party has launched a hunger strike from prison.

European leagues threaten Champions League schedule clashes

The European Professional Football Leagues (EPFL) on Friday threatened schedule clashes on Champions League matchdays in an ongoing dispute with the governing body UEFA.

Danish court revokes citizenship of IS volunteer

A Danish appellate court on Friday stripped a man of his Danish citizenship for volunteering to fight for the extremist Islamic State in Syria.

Banks and Agrokor agree on key elements of standstill agreement

Member banks of the coordinating committee of financial creditors and representatives of the Agrokor food company have in principle agreed on key elements of a standstill agreement, which is expected to be signed later today, announcing changes in the company's management team, Erste Bank said in a statement on Friday afternoon.

Syrian man on trial in Sweden; mosque attack labelled terrorism

A Syrian man went on trial Friday in the southern Swedish city of Malmo, charged with terrorism and arson after an attack last year on a building used as an assembly hall by Shiite Muslims.