People take part in a Brexit referendum anti leave result demonstration in Trafalgar Square, central London Britain, 28 June 2016 after Britain voted 51.9 per cent in favour of leaving the European Union.

Prime Minister David Cameron bid goodbye to his European Union counterparts in a "sad" Tuesday summit in Brussels, while leaders' hands were tied on follow-up action after Britain's momentous decision to leave the bloc.

Britons made the choice in a Thursday referendum that triggered political mayhem in London, caused global market panic and reverberated across the EU. The vote should separate the EU from one of its most influential members.

"Our partners in the EU are genuinely sad that we are planning to leave this organization," Cameron said, adding that he had constructive, positive and calm discussions and was leaving convinced that Britain and Europe should seek "the closest possible relations."

Going into the summit, the British leader faced criticism for leaving to his successor - to be elected in September - the responsibility of starting the exit process by activating Article 50 of the EU treaty, rather than initiating divorce proceedings immediately.

EU Council President Donald Tusk said there was some "understanding that some time is needed" before London can make a move, but said Cameron was asked to "specify as soon as possible" when this would happen. "This was a very clear message," he stressed.

European Commission President Jean-Claude Juncker showed some sympathy for Cameron, who had campaigned for Britain's continued EU membership and announced his resignation after his arguments were rejected by voters.

Juncker said he was amazed that the winning Leave camp was so unprepared for their victory. He described them as "totally unable to tell us what they want."

EU foreign policy chief Federica Mogherini questioned whether Britain really wanted out. "The British people were quite clear on this, but we are receiving contradictory messages from ... a rather confused political scene in London," she said.

But German Chancellor Angela Merkel warned there was no way back. "I see no way to reverse that," she said of the referendum outcome. "This is not the hour for wishful thinking," she added.

Pro EU-integration countries were the most critical of Britain.

"We are not on Facebook where the status is 'complicated,'" Luxembourg Prime Minister Xavier Bettel said. "Either you are married or divorced, but not something in between."

"I don't intend to accept that we are subjected to blackmail inflicted by Britain," added his Belgian counterpart Charles Michel.

But Dutch Prime Minister Mark Rutte said there was no point in giving Cameron "a bollocking" as his country had "collapsed, politically, monetarily, constitutionally, and economically" after the Brexit vote.

Since Thursday, Britain has seen the pound sink to a 30-year low against the dollar and share prices tumble, suffered credit rating downgrades and is threatened with secession by Scotland, which wants to stay in the EU.

European Central Bank (ECB) chief Mario Draghi told EU leaders that Britain's departure could shave 0.3 to 0.5 percentage points from eurozone growth over the next three years, an EU official said.

Draghi predicted "substantially lower growth in [Britain] with a possible negative spillover" to the rest of the world, but that forecast "was less negative than we expected before the Brexit," Tusk said.

Amid uncertainty over its next steps, Britain was warned that it cannot expect easy access to EU membership benefits once it walks out.

"Whoever leaves the family can't expect the same privileges as it had before without also having the obligations," Merkel said at a pre-summit parliament debate in Berlin.

EU leaders exchanged views with Cameron over dinner, after clearing other summit agenda items - including migration and foreign policy - and a meeting with NATO Secretary General Jens Stoltenberg.

The summit was due to resume Wednesday without Cameron, for the remaining 27 leaders to discuss common Brexit responses and ways to strengthen the EU. Another Britain-free summit was announced for September in Slovakia to pursue those discussions.

Latest news

Syrian government vows retribution for Homs attacks that killed 42

The Syrian government vowed retribution for synchronized attacks on Saturday in Homs City that left 42 security personnel dead and reportedly involved up to six suicide bombers.

Between 250,000 and 300,000 Croatians suffer from rare diseases

Rare Disease Day, observed on February 28, was marked in Zagreb's Cvjetni Trg Square on Saturday.

German police shoot man who rammed car into pedestrians in Heidelberg

Police in Germany shot a man who rammed a car into pedestrians in the south-western town of Heidelberg on Saturday.

Egypt's al-Sissi orders cabinet to help Christians fleeing Sinai

Egypt's president Abdel Fattah al-Sissi ordered the government on Saturday to take all necessary measures to help Christians who escaped northern Sinai after the Islamic State militia killed at least six of them over the past month.

SDP MP calls on citizens to raise their voice against restriction of women's rights

Josko Klisovic, a Social Democrat member of the Croatian parliament, on Saturday called on all Croatians to raise their voice against a policy turnaround on women's rights after Croatia took a conservative position in a discussion on human rights in the Council of the European Union.

Egypt court acquits Mubarak's aide of 22 years

An Egyptian court on Saturday acquitted one of ousted president Hosny Mubarak's closest aides, ruling he was not guilty of corruption and illicit profits.

EU ambassador to Albania Romana Vlahutin under 24-hour police protection

EU Ambassador to Albania Romana Vlahutin and her family have been given 24-hour armed police protection due to threats she has been receiving lately, the Austrian paper Der Standard said on Saturday, explaining that the threats were linked to Vlahutin's monitoring of a reform of Albania's judiciary designed to curb corruption in that country.

Italy deports two over suspected contact with Berlin attacker

Italy has deported two Tunisian asylum seekers who have been classed as a danger to national security, the Interior Ministry in Rome said on Saturday.

Croatian PM says HEP IPO most efficient model for INA buyout

Prime Minister and HDZ leader Andrej Plenkovic on Saturday commented on models for buying back Hungarian oil and gas company MOL's stake in INA, saying that an initial public offering of 25% of the HEP power company's shares to obtain funds for INA's buyout was "the most efficient, fastest, simplest and cleanest option with the fewest participants, which enables the state, which is the owner (of HEP), to control the process in its entirety."

Iraqi forces advance in western Mosul amid fierce resistance from IS

Iraqi forces were making advances in western Mosul, entering a new neighbourhood north of the airport, amid fierce resistance from Islamic State militia, a security official said Saturday.

Mugabe says he will not step down as he celebrates 93rd birthday

President Robert Mugabe, the world's oldest head of state, marked his 93rd birthday with lavish celebrations in Zimbabwe on Saturday, despite a deepening economic crisis in the southern African country.

Poll: Majority of Greeks want new savings reforms to avoid elections

Over 60 per cent of Greeks are in favour of striking a new deal to unlock a fresh bailout from creditors as an alternative to snap polls, according to a survey commissioned by the To Vima newspaper.