In an article titled "I penned the suckiest movie ever - sorry!", JD Shapiro likened the 2000 film to a train wreck, adding that the comparison "isn't really fair to train wrecks".
Battlefield Earth, which was based on a novel by the Scientology founder L Ron Hubbard, was named worst film of the decade at last month's Razzie Awards.
Shapiro claimed that interference from John Travolta, the Hollywood actor and prominent Scientologist who played the leading role in the movie, transformed his gritty and compelling screenplay into something "very different".
He wrote: "What my screenplay didn't have was slow motion at every turn, Dutch tilts, campy dialogue, aliens in KISS boots, and everyone wearing Bob Marley wigs."
Shapiro was fired from the project for - he claims - refusing to accept a lengthy list of alterations demanded by the Church. Writing in the New York Post, the writer said that he only seen the finished movie on one occasion, at the premiere, and that this was "was one too many times".
He added: "Now, looking back at the movie with fresh eyes, I can't help but be strangely proud of it. Because out of all the sucky movies, mine is the suckiest."
In his humorous mea culpa Shapiro, whose previous credits include Robin Hood: Men in Tights, said that he first became involved with the Church after reading a magazine article which reported that its "Celebrity Center" in Los Angeles was a good place to meet women.
He agreed to adapt L Ron Hubbard's novel after meeting Travolta, and said that he spent time on board the Church's private cruise ship "walking around in a robe, sandals, smoking Cuban cigars and drinking fine scotch" as part of his research.
Travolta initially described the script as "The 'Schindler's List' of sci-fi" before pushing through amendments that "changed the entire tone" of the finished movie, Shapiro claimed.
The scriptwriter added that he only agreed to have his name attached to the final product to ensure he received full payment for his work.
Battlefield Earth, which is set in the year 3000, chronicles the human rebellion against a nefarious alien race called the Psychlos who have taken over Earth. It cost an estimated $44 million to make and flopped at the Box Office after being panned by critics.
