LONDON — A group of British climate scientists is demanding changes to a skeptical documentary about global warming, saying there are grave errors in the program billed as a response to Al Gore's "An Inconvenient Truth."

"The Great Global Warming Swindle" aired on British television in March and is coming out soon on DVD. It argues that man-made emissions have a marginal impact on the world's climate and warming can better be explained by changing patterns of solar activity.

An open letter sent Tuesday by 38 scientists, including the former heads of Britain's academy of sciences and Britain's weather office, called on producer Wag TV to remove what it called "major misrepresentations" from the film before the DVD release -- a demand its director said was tantamount to censorship.

Bob Ward, the former spokesman for the Royal Society, Britain's academy of science, and one of the letter's signatories, said director Mark Durkin made a "long catalogue of fundamental and profound mistakes" -- including the claim that volcanoes produce more carbon dioxide than humans, and that the Earth's atmosphere was warmer during the Middle Ages than it is today.

"Free speech does not extend to misleading the public by making factually inaccurate statements,'' he said. "Somebody has to stand up for the public interest here."

Durkin called the letter "loathsome."

"This is a contemptible, weasel-worded attempt to gag scientific criticism, and it won't work," he said. "I don't believe they're interested in quality control when it comes to the reporting of science -- so long as it's on their side."

Durkin acknowledged two of the errors highlighted by the scientists -- including the claim about volcanic emissions -- but he described those changes as minor and said they would be corrected in the expanded DVD release.

But the scientists do not want the DVD released without edits to completely remove the material they object to -- something Ward said would fatally weaken the film's argument.

"The fact is that it's a very convincing program, and if you're not very aware of the science you wouldn't necessarily see what the errors are," Ward said. "But the errors are huge. ... Without those errors in, he doesn't have a story."

Ward has also complained to Britain's media regulator, which said it was investigating the matter. British broadcast law demands impartiality on matters of major political and industrial controversy -- and penalties can be imposed for misrepresentations of fact.

The decision to broadcast Durkin's documentary on Channel 4 was an unusual move in a country where the role of man-made carbon emissions in heating the globe is largely taken for granted and politicians regularly spar over which party has the greenest environmental policy.

As for the former vice president, Gore has been hired as an adviser to the British government, which plans to send copies of his film to schools around England.