WASHINGTON (Reuters) - The Federal Bureau of Investigation on Monday raided the offices and home of U.S. President Donald Trump’s personal lawyer Michael Cohen, law enforcement sources said, in a dramatic new development in a series of probes involving close Trump associates.

Cohen’s lawyer, Stephen M. Ryan, said that U.S. prosecutors conducted a search that was partly a referral by the Office of Special Counsel, Robert Mueller.

Mueller is investigating whether members of Trump’s 2016 campaign colluded with Russia during the U.S. presidential election. Trump has called the probe a “witch hunt” and denied any collusion.

The raid could increase legal pressure on the president, because it involves the records of his longtime attorney and indicates a second center of investigations in Manhattan, alongside Mueller’s Washington-based probe.

Cohen has been at the center of a controversy over a $130,000 payment he has admitted making shortly before the 2016 election to porn star Stormy Daniels, who has said that she had sex once with Trump in 2006 and was paid to keep quiet about it.

Trump reacted with unusually harsh language to news of the raid.

“It’s a disgraceful situation. It’s a total witch hunt. I’ve been saying it for a long time,” Trump said at the opening of a meeting with military and national security advisers to discuss Syria.

Asked whether he would fire Mueller, Trump said, “Well, I think it’s a disgrace what’s going on. We’ll see what happens.”

Trump cannot fire Mueller directly, but he could order Deputy Attorney General Rod Rosenstein, who oversees the special counsel’s probe, to end it, or Trump could fire Rosenstein if he refuses.

In a Tweet, Senate Democratic leader Chuck Schumer warned Trump against interfering.

“If @realDonaldTrump is thinking of using the FBI raid to fire Special Counsel Mueller or otherwise interfere with the chain of command in the Russia probe, we Democrats have one simple message for him: don’t,” Schumer said.

Under federal regulations, if Mueller comes across information that is not directly related to his Russia-focused investigation, he must confer with Rosenstein. Rosenstein could direct Mueller to either investigate the issue himself or refer it to another law enforcement authority.

The raids were first reported by The New York Times.

POSSIBLE BANK, TAX FRAUD

“Today, the U.S. Attorney’s Office for the Southern District of New York executed a series of search warrants and seized the privileged communications between my client, Michael Cohen, and his clients,” Ryan said in a statement.

“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,” Ryan said.

Federal prosecutors are investigating Cohen for possible bank and tax fraud, and for possible campaign law violation in connection with the Stormy Daniels payment, and perhaps other matters having to do with foreign support to Trump’s 2016 campaign, a second source familiar with the investigation said.

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The New York Times reported on Monday evening that Mueller is investigating a $150,000 payment made in September 2015 by a Ukrainian billionaire, Viktor Pinchuk, to Trump’s charitable foundation in exchange for a 20-minute video appearance by Trump at a conference in Kiev.

Cohen solicited the Pinchuk donation, the Times reported, citing three sources it said were briefed on the matter, although it was not immediately clear if Monday’s raids sought information on that issue.

Trump had declared his candidacy for president in June 2015.

Cohen did not immediately respond to Reuters for a request for comment on the raids. A spokesman for Mueller had no comment.

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Cohen has said that he paid the $130,000 settlement money to Stormy Daniels, whose real name is Stephanie Clifford, from his own pocket through a personal home equity loan. Trump, in comments to reporters on Air Force One last week, said that he did not know about the payment.

According to a person familiar with the matter, FBI agents executed a search warrant at the New York offices of the law firm Squire Patton Boggs on the 23rd floor of 30 Rockefeller Plaza, where Cohen has an office.

The agents went there about 9:00 or 9:30 a.m. and worked for several hours, the person said.

A source familiar with the investigation said the raid was conducted without prior warning.

Federal agents also raided a room at the Loews Regency Hotel on Park Avenue in Manhattan where Cohen has been staying while his apartment is being renovated, The New York Times reported, citing an unnamed person.

The FBI and U.S. Attorney’s office on Monday also sought any emails between former White House communications director Hope Hicks and Cohen about a false and misleading account that Trump helped prepare of a June 9, 2016, meeting between Trump’s son Donald Trump, Jr. and son-in-law Jared Kushner and a group of Russians who had promised “dirt” on Democratic presidential candidate Hillary Clinton, the first source familiar with the investigation said.

Such emails would not be covered by attorney-client privilege, this source said, because Cohen did not represent Hicks.

Ryan, in his statement, called the search warrants executed by the U.S. Attorney’s office in Manhattan “completely inappropriate and unnecessary.”

“It resulted in the unnecessary seizure of protected attorney client communications between a lawyer and his clients,” he said.

Attorney-client privilege is intended to encourage open communications between lawyers and their clients, so that lawyers can provide sound legal advice.

But the privilege is not absolute, and there is an exception for communications made to further a crime.

“The crime-fraud exception means the privilege does not apply to communications between the client and the attorney, if they are evidence of an ongoing crime or fraud, not just a past crime or fraud,” said Christopher Slobogin, a professor at Vanderbilt Law School specializing in criminal procedure and evidence.

A spokesman for Squire Patton Boggs said in a statement that its arrangement with Cohen is ending.

“The firm’s arrangement with Mr. Cohen reached its conclusion, mutually and in accordance with the terms of the agreement,” the statement said. “We have been in contact with Federal authorities regarding their execution of a warrant relating to Mr. Cohen. These activities do not relate to the firm and we are in full cooperation.”

Ryan said that Cohen has cooperated with authorities and turned over thousands of documents to congressional investigators for their own probes into Moscow’s alleged efforts to influence the U.S. election.