The Arts Council has encountered ridicule and anger over attempts to force theatre and museum trustees to disclose their sexuality to obtain funding.

New grant forms require arts organisations to state how many board members are bisexual, gay, heterosexual, lesbian or "not known".

Sir Ian McKellen and Vanessa Redgrave are among leading figures of the stage who have condemned the move, which appears to discriminate against mainstream venues.

Oscar-nominated Sir Ian, who is gay, said: "It sounds extraordinary. It shouldn't be on a form. It's quite inappropriate."

Redgrave said: "Everyone should put down 'trisexual', whoever you are.

Britain has become the world's leading population of trisexuals."

They were joined in their condemnation by Christopher Hampton, whose adaptation of God of Carnage, starring Ralph Fiennes, has just opened at the Gielgud Theatre. He said: "It's bureaucracy and political correctness gone mad."

Playwright Michael Frayn ridiculed the questions, suggesting boxes to "specify how many members are longsighted or short-sighted, how many wear black socks or brown socks".

The council has defended the funding process saying it was necessary to see if the applicants were representative. Audrey Roy, the council's director of grants, said: "We see diversity as broader than race, ethnicity, faith and disability."

The application form states that the sexual orientation question is for government purposes only and will not affect the grant decision, however the Department for Culture, Media and Sport has contradicted that claim.

A DCMS spokesman said: "We appreciate that as a responsible public body they need to monitor their overall grant-making programmes. But it is absolutely not the case that sexual orientation monitoring is a government requirement."

The new requirement has attracted widespread criticism with Nicolas Kent, artistic director of the Tricycle Theatre in Kilburn, saying: "This is ridiculous.

It has no relevance. The Arts Council is prone to huge overregulation, as seems to be the case with the whole of society.

"But the Arts Council has caught it very badly. They should advance the arts instead of ticking every box they invent."

Referring to the council's announcement of grant cutting, gay actor Simon Callow, said: "The Arts Council comedy continues. What is difficult is to divine to what conceivable use they could put this information."

The council said the answers were confidential and exempt from release under the Freedom of Information Act. It said it does not issue guidelines on how to persuade board members to reveal details of their sex lives.

The council has come under heavy fire this year from high-profile artists over a series of grant cuts in February.

More than 50 arts organisations in London lost millions of pounds in funding after it announced a restructure of funding.

Many have appealed and one leading venue, the Watermans Arts Centre in Brentford, is threatening to take the council to judicial review for wiping out its entire £400,000 grant.

Labour peer Genista McIntosh, former executive director of the National Theatre, recently began investigating the council's handling of its last spending round to see what lessons can be learned for next time.

The council said the review had been planned and was not a response to the criticism.

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