WASHINGTON — Michael T. Flynn, the former national security adviser, backed off his planned testimony in a federal case against a former associate, according to court documents unsealed on Tuesday.

Mr. Flynn had previously admitted that he lied on foreign lobbying disclosure forms submitted to the Justice Department but now is blaming his former lawyers, accusing them of filing inaccurate forms without his knowledge. He did not dispute that the filing itself contained false information.

His latest gambit could provoke another dramatic and risky confrontation with the federal judge who delayed sentencing Mr. Flynn last year in a separate case so he could continue to cooperate with the government in the hopes of a lighter punishment. And it was the latest strange turn in a prosecution that should have run its course without much drama after Mr. Flynn pleaded guilty in December 2017 to lying to investigators and agreed to cooperate with the special counsel’s investigators.

Mr. Flynn’s lawyers might not care what the judge does if they believe President Trump will pardon his former national security adviser. Mr. Trump has said that Mr. Flynn is a good man who was treated poorly but has not said whether he will pardon him.