Rowan Atkinson, the comedian, led a coalition of Britain's most prominent actors and writers to Parliament today in an attempt to force a review of a controversial Bill designed to combat racial and religious hatred.

The Blackadder star, 50, said that the Racial and Religious Hatred Bill, which gets its second reading in the Commons tomorrow, would give religious groups a "weapon of disproportionate power" whose threat would engender a culture of self-censorship among artists.

He was accompanied by Nicholas Hytner, the director of the National Theatre, Ian McEwan, the Booker Prize winning author, and a coalition of creative artists, lawyers and MPs who oppose the Bill, tabled by Charles Clarke.

Mr Hytner used the example of Friedrich Schiller’s Don Carlos, written 200 years ago. He said that the play - which enjoyed a successful run at the Gielgud Theatre earlier this year - "unambiguously" promoted hatred of Roman Catholicism.

The Home Secretary argues that the new law is needed to tackle racists who since the September 11 attacks have increasingly targeted Muslims as a faith group. He says that it will end an anomaly under which Jews and Sikhs are protected by laws against incitement to racial hatred, while other religious groups are not.

But opponents of the Bill are instead backing an amendment to the race-hate laws to make clear that they cover attacks on religious beliefs only if they are a proxy for racial attacks.

Bob Marshall-Andrews, a Labour MP and QC, said that there was growing pressure among his backbench colleagues for Tony Blair to grant a free vote on the Bill. Some 25 Labour MPs rebelled against a three-line whip to back the amendment in the last Parliament.

Dominic Grieve, the Shadow Attorney-General, said that Tories would vote against the Bill.

Speaking at a press conference to launch the amendment in a parliamentary committee room, Atkinson conceded that only a handful of the jokes he has told in a career full of parodies of priests would have risked prosecution.

But he warned of the dangers of self-censorship, as writers, comics and producers avoid material that might stir up protests and threats of prosecution from religious groups.

The Government insists that artists and writers would not face court under the Bill, because cases would only go forward if they won the approval of the Attorney-General.

But Atkinson gave warning that this approach would last only until "some political imperative suddenly makes it rather desirable for the Government to prosecute a few writers or journalists or playwrights in their desire to ingratiate themselves with a particular religious community".

He added: "The excuse for this legislation is that certain faith communities have suffered harassment and a law is required to address it. That in itself is a perfectly good reason, and it is what this amendment which we are launching today addresses. But it is not the real reason behind it.

"The real reason, it seems to me, is that since the day of the publication in 1989 of Salman Rushdie’s book The Satanic Verses, a hard core of religious thinking in this country has sought a law to grant religious beliefs and practices immunity from criticism, unfavourable analysis or ridicule."

McEwan predicted that anxiety over possible prosecution would make it much more difficult, if the Bill is passed, to raise funding for controversial productions such as Jerry Springer: The Opera, which sparked a storm of complaints from religious groups yet has won a string of awards.

He said: "I thought that we had settled this matter long ago, and agreed that the best guarantee of religious freedom is secular governance. Not all religions can be true. It is possible none of them is. All that can guarantee tolerance within that situation is a secular state that guarantees equal treatment."

Mr Hytner said that any suggestion that the law barred the giving of offence would be "grievously damaging" to the theatre, which since the days of the Greeks had thrived on questioning, undermining and ridiculing religious beliefs.

"There is a recent West End hit which would fall foul of this legislation if anybody cared to bring a prosecution of it, and that is Schiller’s Don Carlos, which promotes hatred of Roman Catholicism unambiguously," he said.

Shami Chakrabarti, director of civil liberties group Liberty, said: "There is a distinction between definitions of racial hatred and religious hatred. One refers to an immutable characteristic about which there is little debate to be had, and the other to a body of ideas.

"People in a democracy have the right vigorously to debate, and even denigrate, others’ ideas."

If passed, the Bill would "excite all sorts of expectations that no sensible Attorney General could ever meet", she said, warning it was "likely to make the existing problem of Islamophobia worse, not better".

Mr Marshall-Andrews predicted that giving the Attorney General the final say on whether prosecutions go ahead would turn him into "the whipping boy for religious bigotry", inundated with complaints from fundamentalist groups and then lambasted for turning them down.

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