(CNN) Federal court documents unsealed Wednesday inadvertently revealed several names of potential witnesses in Paul Manafort's foreign lobbying criminal case, including two people Manafort and his associate Konstantin Kilimnik allegedly pressured to change their story before trial.

The two witnesses Manafort and Kilimnik are accused of tampering with are Eckart Sager and Alan Friedman, former journalists turned public relations specialists who worked with Manafort, the documents said. Sager is a former CNN employee.

Manafort and Kilimnik called and texted them, prosecutors said, after Manafort's deputy Rick Gates flipped to a guilty plea in February and prosecutors said they knew about Manafort's foreign lobbying efforts in the US that were hidden from federal investigators.

Manafort has pleaded not guilty to the foreign lobbying criminal charges. He and Kilimnik have not yet entered their pleas to the witness tampering allegations.

A memo Manafort received was attached to the court filing Wednesday. It described an effort he, Friedman and Sager spearheaded in 2012 for Ukrainian clients that aimed to bring together European politicians to lobby US members of Congress.

Read More