A dozen audio recordings seized by the FBI from President Donald Trump's former lawyer, Michael Cohen, were forwarded to federal prosecutors after lawyers dropped challenges on attorney-client privilege grounds, a former judge revealed Monday.

The recordings were among millions of files taken from Cohen in April as part of a criminal probe of his business practices.

Barbara Jones, a court-appointed lawyer and former Manhattan federal judge helping to decide which of the seized files are protected by privilege, said in a court filing that prosecutors received the recordings on Friday after attorneys for Trump, Cohen and the Trump Organization dropped privilege claims.

The same day, Trump attorney Rudy Giuliani said Cohen had recorded a conversation in which the president had discussed a potential payment to squash the story of a former Playboy model who said she had an affair with Trump.

Giuliani said the brief recording shows Trump did nothing wrong.

"The transaction that Michael is talking about on the tape never took place, but what's important is: If it did take place, the president said it has to be done correctly and it has to be done by check" to keep a proper record of it, Giuliani said.

In a weekend tweet, Trump called Cohen's practice of recording conversations "totally unheard of & perhaps illegal."

Attorney Lanny Davis, speaking on Cohen's behalf, has said what is on the tape will not harm Cohen.