By Emily Stephenson and Noeleen Walder

(Reuters) - Republican White House hopeful Donald Trump is seeking $10 million in damages from a fired former employee, shedding light on a campaign that has at times seen high-profile exits and internal fights spill over into public view.

Trump in May started arbitration proceedings against Sam Nunberg, a former adviser who was fired in 2015, accusing him of violating a confidentiality agreement, according to a court filing obtained by Reuters.

"He has a confidentiality agreement which he has repeatedly breached, and we've taken action to enforce it," said Alan Garten, general counsel with the Trump Organization who is representing the campaign in the arbitration.

Nunberg did not respond to a request for comment.

The flare-up comes after a period in which campaign in-fighting led Trump to fire some top aides, including national political director Rick Wiley and campaign manager Corey Lewandowski. Other staffers have separately resigned from Trump's campaign.

Trump's legal conflicts, which also include a lawsuit over his Trump University real-estate seminars, have at times distracted public attention from his campaign.

Nunberg in court documents dated Tuesday accused Trump of starting arbitration proceedings to retaliate against him for switching his support to rival presidential hopeful Ted Cruz during the Republican primaries. Cruz dropped out of the race in early May.

Garten said the suit was unrelated.

Nunberg also said Trump tried to use the arbitration to "cover up media coverage of an apparent affair" between two members of his presidential campaign staff.

"The Trump campaign is attempting to bring a frivolous and retaliatory arbitration proceeding against me essentially to punish me and shut me up," Nunberg said in an affidavit accompanying his petition to halt the arbitration proceedings.

The petition was filed on Tuesday in New York state court in Manhattan. The Trump campaign fired Nunberg in August 2015 after the discovery of Facebook posts that critics deemed racist. Nunberg at the time denied he wrote the posts.

He said in the court filings that Trump accused him of being the source for a New York Post story in May that recounted a public argument between Lewandowski, who was then with the campaign, and Hope Hicks, Trump's spokeswoman.

In the affidavit, Nunberg said the argument was part of an "sordid and apparently illicit affair" between the two. He denied being the source for the New York Post story, saying the argument occurred in public and others saw it.

Garten called the allegation "categorically untrue" and said Nunberg had recently asked for his job back.

"This is an individual who time and time again has demonstrated that he will say anything that is outrageous, regardless of whether it's factually accurate, to get his name out there and create trouble," Garten said.

Hicks and Lewandowski did not respond to requests for comment.

(Reporting by Emily Stephenson and Noeleen Walder; Additional reporting by Emily Flitter; Editing by Leslie Adler)