There is "no information" to support US President Donald Trump's claims that the FBI wiretapped his offices, Director James Comey says.
Asked directly about tweets from the president claiming his predecessor Barack Obama had ordered the wiretapping of his office, Comey told lawmakers: "I have no information that supports those tweets and we have looked carefully inside the FBI.
"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.
Trump had charged in a series of tweets earlier this month: "Terrible! Just found out that Obama had my 'wires tapped' in Trump Tower just before the victory. Nothing found. This is McCarthyism!"