President Trump claimed at the weekend that his predecessor Barack Obama had his 'wires tapped' in Trump Tower
The FBI Director James Comey is said to have asked the US Justice Department to publicly refute accusations by President Donald Trump that Barack Obama had his 'wires tapped', according to US media reports.
According to the New York Times, Mr Comey is urging the department to reject the claims because "it falsely insinuates that the FBI broke the law".
The reported intervention follows comments from James Clapper - the director of national intelligence in the Obama administration - who denied there was an order for surveillance at Trump Tower.
In an interview with NBC's Meet The Press, Mr Clapper said that in the national intelligence work he oversaw, there was "no such wiretap activity mounted against the President, the President-elect at the time, as a candidate or against his campaign".
Mr Clapper, who left the White House on 20 January when Mr Trump took office, said he would have known about such an order.
"Absolutely, I can deny it," he said.
The White House has requested that Congress investigate Mr Trump's accusation that his predecessor ordered a wiretap of the phones at Trump Tower - his New York residence and campaign headquarters - the month before the country went to the polls.
Mr Trump has not offered any evidence to support his claims, and Mr Obama has rejected the allegations, with a spokesman describing them as "simply false".
White House press secretary Sean Spicer said in a statement on Sunday: "Reports concerning potentially politically motivated investigations immediately ahead of the 2016 election are very troubling."
He said the President had requested "that as part of their investigation into Russian activity, the congressional intelligence committees exercise their oversight authority to determine whether executive branch investigative powers were abused in 2016".
It was unclear which reports Mr Spicer was referring to, but he added neither the White House or the President would be commenting further on the matter until the investigation concluded.
House Intelligence chairman and Republican Devin Nunes said in a statement that his committee "will make inquiries into whether the government was conducting surveillance activities on any political party's campaign officials or surrogates".
Senator Tom Cotton, a Republican member of the Senate Intelligence Committee, said his panel would also look at the allegations as part of its investigation into Russian interference in the presidential election.
Mr Cotton said: "We're going to follow the facts wherever they lead us and I'm sure that this matter will be a part of that inquiry."
The Democratic leader in the House of Representatives, Nancy Pelosi, said Mr Trump's claims were "just ridiculous", telling CNN that he was following the playbook of making something up, having the media report it and then saying everybody is writing about it.
She said having people "talking about what you want them to be talking about" was a "tool of an authoritarian".
Mr Trump made the allegations against Mr Obama in a series of tweets on Saturday, amid growing scrutiny of his campaign's ties with Russia.
He wrote: "Terrible! Just found out that Obama had my 'wires tapped' in Trump Tower just before the victory. Nothing found. This is McCarthyism!"
The President added: "Is it legal for a sitting president to be 'wire tapping' a race for president prior to an election? Turned down by court earlier. A NEW LOW!"
"I'd bet a good lawyer could make a great case out of the fact that President Obama was tapping my phones in October, just prior to election!"
A spokesman for Mr Obama has dismissed the claims, insisting it was "a cardinal rule" of his administration that no White House official ever interfered with any independent investigations led by the Department of Justice.
Earlier, Republican senator Ben Sasse called the US President's surveillance claims serious and said the public deserved more information.
The politician said it was possible Mr Trump had been illegally tapped and he should explain what sort of device it was and how he knew about it.
Under US law, a federal court would have to have found probable cause that the target of the surveillance is an "agent of a foreign power" before authorising such an order.