Donald Trump escalated his war with Barack Obama as a committee in Congress agreed to look into his claims that the former president and his administration abused executive powers in last year’s election.

In his latest high-stakes salvo, and as he prepared to roll out a revised travel ban on Muslim-majority countries, Mr Trump had called for a congressional investigation after alleging that he was the victim of a dirty tricks campaign akin to Watergate.

His move came a day after he claimed his predecessor ordered a wiretap of the phones at Trump Tower in New York, Mr Trump’s campaign headquarters.

James Comey, the FBI director, asked the Justice Department this weekend to publicly refute Mr Trump’s assertion, unnamed officials told the New York Times on Sunday.

Mr Comey and the Justice Department have been working to reject the claim because it falsely insinuates that the FBI broke the law, it was reported.

Neither the FBI nor the Justice Department have so far released any public statement.