The lawyer for adult film star Stormy Daniels, who claims to have had an affair with US President Donald Trump, filed court papers Sunday demanding that Trump submit to questions about the $130,000 hush money paid just before the 2016 presidential election.
The dispute centers on whether the agreement is valid and if the matter should be settled in open court or private arbitration.
Trump asserted to the press on Air Force One on Thursday that he did not know about the payment to keep the actress, whose real name is Stephanie Clifford, quiet.
The White House has denied that Trump ever had sex with Clifford.
The actress said in a recent CBS "60 Minutes" interview that they had sex one time and she later felt threatened to sign the agreement.
Trump's lawyers are seeking $20 million in damages for Clifford's violations of the agreement.