travolta042412_01_X17travolta230.jpgJohn Travolta and his lawyer Marty Singer are being sued by author Robert Randolph ... the man who wrote the book "You'll Never Spa In This Town Again."

Aside from writing the book, Randolph also contributed to a 2010 Gawker article called "The Secret Sex Life of John Travolta" which made allegations that Travolta had gay encounters in bath houses.

As a result, Singer sent a response to the website saying the allegations against his client were false. Randolph says the attorney also made "defamatory statements" against him ... alleging that the author had gone to a mental institution. Randolph's lawsuit says the following:

    "Several of the statements made by Defendant Singer, on behalf of Defendant Travolta, are untrue and amount to defamatory statements sought to disparage the quality of [Randolph's] property and reputation and to induce members of the public to believe [Randolph] is an unreliable source and thus abstain from purchasing" his book."

In response, Travolta's rep released the following statement:

    "The lawsuit filed by Robert Randolph is absurd. The suit is based on a privileged communication, and it will promptly be thrown out by the court. To evaluate the credibility of Robert Randolph and his ridiculous lawsuit one need look no further than his own statements published on his website stating that he sustained “permanent brain damage” and had to “retrain” his brain."

Click thru to read the rest of the statement.