Stephen Rea seems to relish playing glum anti-heroes on screen. But, as he tells Geoffrey MacNab, playing a comic part in the theatre, with the immediacy of a live audience, is more rewarding.

Stephen Rea is mumbling in the direction of his feet: "They do say this thing about me being . . . hangdog, melancholy. It drives me insane."

Even as he complains about being typecast as the long-suffering Chekhovian or Celtic anti-hero, he sounds ever more despondent. "I'd like to do more comedy," he says gloomily, his countenance clouding over. "I can't help it that my face is like this, but Chekhov isn't depressive at all. It's very active. It may be agonising, but it's also very funny. . . sometimes."

The Belfast-born actor is in familiar groove in his new film, A Further Gesture. The very first shot of the movie is a big close-up of Rea looking, as usual, careworn and infinitely sad. His face is, as Martin Scorsese once put it of John Garfield, "a landscape of moral conflict". He plays Dowd, a long-term IRA prisoner. The part might almost be a continuation of his role as IRA volunteer Fergus in Neil Jordan's The Crying Game. Just as he ends that film in prison, he begins this one behind bars. Just as Fergus is displaced from Ireland to London, Dowd too is forced into exile - this time, he flees to New York after escaping prison.

Ronan Bennett may have written the script for A Further Gesture but the character of Dowd originated with Rea. "I had the idea of a guy for whom an escape from prison is not actually a release but a move into a further prison or a move to suicide - a man whose options are pared down to barely nothing."

Dowd, he explains, is a burned-up case: he retains the capacity for violence, but has lost the idealism which originally fired his involvement in politics. "It's to do with being dead inside. It sounds so deeply, deeply pessimistic - and, of course, it is," he laughs. "He has no possibility of redemption."

A Further Gesture does not attempt to make Dowd falsely sympathetic. We see him pistol-whip a prison officer and set about a New York drug- dealer's head with a fire extinguisher. Nor does the film engage with the minutiae of "the troubles". Instead, it deals with Dowd's predicament on an abstract, personal level. Rea, an actor who has refined impassivity into an expressionistic art, plays him deadpan. "If you look at different takes," he says, "you see that the ones in which you do least are usually the most effective. Stillness is always more involving. I try to go into every scene not with passive melancholia as the condition but active intellectual intention. Provided you're thinking, the camera gets it."

With his wistful understatement, he has the knack of making the most hard-bitten character seem vulnerable and ingenuous. In A Further Gesture, in spite of everything, we end up rooting for Dowd. Even so, Rea believes the very fact that Dowd is ex-IRA is likely to put off British audiences.

Michael Collins, he argues, was easier for the Brits to digest because an Irishman, De Valera, was chosen as villain, and the emphasis was on the Civil War - "on how bad the Irish were to each other rather than how bad the British were to the Irish".

It is instructive to compare Dowd with Rea's saxophonist Danny in his first movie, Neil Jordan's Angel (1982). Like Dowd, the musician is destroyed spiritually by his contact with violence. He ends up swapping his saxophone for a machine gun as he seeks to avenge the pointless death of a mute teenage girl at the hands of terrorists. ("I'll teach you to sing," he mutters plaintively as he holds the dead girl's crumpled body in his arms.) What might have been a conventional action-thriller is turned by Jordan and Rea into a poetic lament. Rea is the same mournful, introspective screen presence as in A Further Gesture, and even shows a similar line in fatalistic humour. He just looks younger.

Still to suggest that he is only able to play saturnine Celts is to underestimate his range. He was a bespectacled, librarian-type in Michael Collins and a truculent con-artist in Trojan Eddie. He has done comic turns for Mike Leigh (Life Is Sweet, Four Days in July), he has played wolves and vampires, and was very funny as the middle-class, North London-based Irishman negotiating a mid-life crisis in Les Blair's Bad Behaviour. He stars in Neil Jordan's film version of Patrick McCabe's novel, The Butcher's Boy (to be released early next year), and was recently in Hollywood to shoot a cameo in Jordan's new film, In Dreams, which stars Annette Bening and is being produced by Spielberg. With Field Day, the company he, Seamus Heaney and Brian Friel set up in 1980, he is also currently producing a feature-length documentary to mark the bicentenary of 1798 rebellion in Ireland.

"It was a great enlightenment project, something that united the whole of Ireland. After it failed, everything broke down into Catholic nationalism and royalism. At this moment, when Ireland seems about to break into something new, we thought it was worth looking back at a time when people seemed to have found a way out of the sectarian division of the country."

Rea's filmography may be varied, but it looks distinctly patchy by comparison with his stage work. As he acknowledges, his best movies have all been with Neil Jordan. "Neil does great stuff and I love working with him, but I can't just rely on that."

After the success of The Crying Game in the US, Rea tried a "couple of Hollywood-type things" he wasn't happy with, but quickly lost heart with the quality of the material the studios were pushing his way. He hasn't abandoned cinema - he is shortly to start work on a US indie film called Hacks - but he sounds more enthusiastic about theatre than films. As he puts it, "I've never been in a bad play. There might have been bad productions and I might have been bad in them, but I've never been in a play that wasn't interesting or worthwhile doing on some level. So much more can go wrong with a movie, because the distance between the hand and the mouth is so much greater. It has to go through so many more processes before it can reach its public."

He thrives on the immediacy of a live audience. "With Field Day, we'd often play places where they hadn't seen professional actors in 30 years. Everyone in the community would come and see you. That's very exhilarating. . . We were trying to address what kind of country Ireland was; to address questions of identity, the colonial experience and language. We felt we were in a country moving from partial independence into a post-colonial state."

Ask him about the trappings of show business and he seems a little baffled. "That makes us sound like we're all very frivolous. People are longing to get into the theatre and movie world. Sometimes I think my attitude is far too serious. A little frivolity wouldn't be a bad thing."

'A Further Gesture' opens next week.