Michael Keaton was a diva in a movie set. The erstwhile "Batman" star is being sued by the producers of "The Merry Gentleman," a film he directed and starred in, for allegedly being difficult on the production in 2007.

Production company Merry Gentlemen, LLC claims in a lawsuit it filed in federal court in Illinois that it lost more than $4 million because the 61-year-old actor kept making demands on the film.

"The Merry Gentleman" is the unlikely friendship of a hitman and woman who unknowingly witnessed one of his crimes. Keaton directed the film and starred along with Kelly Macdonald, Tom Bastounes, and Bobby Cannavale.

It was presented at the Sundance Film Festival in 2008 to moderately positive reviews, but it raked in just a little over $320,000.

The suit, obtained by TMZ, cites examples of Keaton's alleged diva-esque behaviour during the production of the film, which include the one time when the company spent time, energy, and money into building an editing facility in California for Keaton, only to build another one in Montana to accommodate Keaton's work and play time.

There was another incident cited in the paper, in which Keaton threatened to sue the producers after they cut their own version of the movie. The lawsuit claims that the actor would use his connections and have the movie pulled out from the 2008 Sundance Film Festival unless they use his directorial cut instead.

Keaton apparently continued being difficult, and was even less than enthusiastic when he promoted the movie on Good Morning America.

The production company is suing for unspecified damages.