UPDATE 1-NY appeals court rejects Trump bid to halt defamation lawsuit

(Adds details about lawsuit)

NEW YORK, May 17 (Reuters) - A New York state appeals court on Thursday rejected U.S. President Donald Trump's bid to halt a defamation lawsuit by a former contestant on his reality TV show "The Apprentice" who accused him of making unwanted sexual advances on her.

In a one-page order, the Appellate Division in Manhattan did not explain why it denied Trump's motion to stay the lawsuit by Summer Zervos.

The White House was not immediately available for comment.

Trump has been challenging a March 20 ruling by Justice Jennifer Schecter of the State Supreme Court in Manhattan, which rejected his claim that as president he was immune from lawsuits over private conduct predating his entering the White House.

Zervos first came forward in October 2016, a month before the presidential election, following the release of a 2005 "Access Hollywood" recording in which Trump spoke in vulgar terms about trying to have sex with women.

While Trump apologized for his comments, Zervos accused him of having kissed her against her will at a 2007 meeting in New York, and later groped her at a Beverly Hills hotel.

During his campaign, Trump repeatedly said all accusations made by women after the "Access Hollywood" recording became public were "lies," and republished on Twitter a post that called Zervos' accusations a hoax.

Zervos has said those denials amounted to defamation. (Reporting by Jonathan Stempel in New York Editing by Chizu Nomiyama and Richard Chang)