Federal investigators on Friday confirmed in a new court filing that Michael Cohen, President Donald Trump's longtime personal lawyer, is the subject of a criminal investigation.

The investigation is separate from the special counsel Robert Mueller's Russia probe.

Raids on Monday of Cohen's office and hotel room were the result of a monthslong investigation, the filing says.

Federal investigators confirmed on Friday that President Donald Trump's longtime personal lawyer, Michael Cohen, is the subject of a criminal investigation.

The confirmation was in a response by the US attorney's office for the Southern District of New York to Cohen's motion seeking to prevent prosecutors from reviewing some evidence obtained on Monday by the FBI in raids of his hotel room and office.

Investigators said the raids were "the result of a monthslong investigation into Cohen, and seek evidence of crimes, many of which have nothing to do with his work as an attorney, but rather relate to Cohen's own business dealings."

The filing says this investigation into Cohen is separate from the special counsel Robert Mueller's inquiry into Russia's interference in the 2016 US election.

The FBI on Monday morning raided Cohen's Manhattan office, home, and hotel room. Investigators took records related to several topics, including a $130,000 hush-money payment to the adult-film star Stormy Daniels just before the 2016 election, The New York Times reported.

Federal prosecutors obtained a search warrant after Mueller sent a referral, said Stephen Ryan, Cohen's lawyer.

Reports earlier Friday said Cohen had asked a federal judge to block the Justice Department from viewing his communications with Trump.

Read the full filing: