A former Playboy model who said she had an affair with US President Donald Trump has filed a lawsuit in California to release her from a legal agreement requiring her to stay silent.

It makes her the second woman this month to contest an arrangement to keep quiet about an alleged extramarital relationship with Trump.

Karen McDougal filed the lawsuit in Los Angeles Superior Court against American Media, publisher of the National Enquirer, which paid her $US150,000 in 2016 to keep quiet on the matter, according to a copy of the lawsuit provided by her lawyer, Peter Stris.

The lawsuit comes a month after the New Yorker reported on the alleged affair and a move by American Media to pay McDougal for exclusive rights to her story, which it never published.

The New Yorker article noted that American Media head David Pecker has described Trump as a “Personal friend”.

Adult film actress Stormy Daniels, whose real name is Stephanie Clifford, sued the president on March 6, stating that Trump never signed an agreement for her to keep her quiet about an “Intimate” extramarital relationship between them.