THE Federal Bureau of Investigation has raided the offices of Donald Trump’s personal lawyer Michael Cohen, prompting a furious response from the US President.

Mr Cohen has been at the centre of a controversy surrounding the payment of a porn star who has alleged that she had sex with Mr Trump and was paid money shortly before the 2016 election to keep quiet about it.

Stephen Ryan, Cohen’s lawyer, confirmed to The New York Times that a raid had taken place and that certain “communications” had been seized.

“I have been advised by federal prosecutors that the New York action is, in part, a referral by the Office of Special Counsel Robert Mueller,” said Mr Ryan.

Trump called it a “disgrace” that federal agents “broke into” the office of his personal attorney. He also called special counsel Robert Mueller’s investigation “an attack on our country.”

“The decision by the US Attorney’s Office in New York to conduct their investigation using search warrants is completely inappropriate and unnecessary,” Ryan said in a statement. “It resulted in the unnecessary seizure of protected attorney client communications between a lawyer and his clients.”

The raid creates a new legal headache for Trump even as he and his attorneys weigh whether to agree to an interview with Mueller’s team, which in addition to investigating potential ties between Russia and the Trump campaign is also examining whether the president’s actions constitute obstruction of justice.

Mr Ryan said the search warrants were executed by the office of the US Attorney for Southern District of New York but they are “in part” related to special counsel Robert Mueller’s investigation.

Mr Cohen is Mr Trump’s longtime personal lawyer. He has been under heavy public scrutiny in recent months for his payment of $USD130,000 ($168,000) to porn star Stormy Daniels, who claims to have had an affair with Mr Trump in the mid-2000s.

There have been few signs that Mueller was interested in investigating the payment, though. One Mueller witness, former Trump aide Sam Nunberg, recently connected the special counsel with the payment, saying in an interview on MSNBC last month that prosecutors had asked him about it.

Trump answered questions about Daniels for the first time last week, saying he had no knowledge of the payment made by Cohen and he didn’t know where Cohen had gotten the money. The White House has consistently said Trump denies the affair. Daniels has said she had sex with the president in 2006.