Owen Wingrave is often described as Benjamin Britten's pacifist opera, but it is far from peaceful.

Neil Bartlett's new production - first seen in Aldeburgh in June and coming to the Edinburgh International Festival later this month - is an intense and uncomfortable theatrical experience. It makes no attempts to quell the psychological violence at the heart of the work; it is thorny, unflinching and very powerful.

Britten composed the score in the late 1960s, having been commissioned by the BBC to create an opera specifically for television (a certain David Attenborough, then controller of BBC2, was responsible for the commission). The chilling plot comes from Henry James, whose writing had provided the basis for Britten's earlier, equally creepy chamber opera The Turn of the Screw. Again Britten asked the librettist Myfanwy Piper to work on a reduction; again she delivered a text that is dense with lean, potent imagery.

The story is simple. Owen grows up in a famous military family but decides he doesn't believe in war and announces to his tutor that he won't be going to Sandhurst as planned. Back at the Wingraves' crumbling country home, Paramore, Owen is disowned by his family and his fiancee - "the very portraits glower at me on the walls," he sings. As in The Turn of the Screw, there is an eerie supernatural dimension: a locked room at the heart of Paramore, in which (so family legend has it) a previous Wingrave boy was beaten to death for refusing to fight. This legend haunts Owen to the end.

Britten and Piper worked on the opera from 1968 until it was recorded at Snape Maltings in 1970. Meanwhile, American military planes were flying low over Suffolk's skies and news bulletins showed rolling images from the Vietnam war, so it is hardly surprising that the opera is infused with Britten's deep-held pacifist values.

Bartlett describes Owen as one of Britten's most candid self-portraits, of "a young man trying to find himself, to reject everything the patriarchy is trying to teach him and to find against all odds an original way of living at peace amongst men".

Bartlett's production is sparse and challenging. It fixates on the legend of the locked room and frames an otherwise bare stage with a cast of silent soldiers who simulate acts of child abuse. Bartlett doesn't apologise for what have often been described as the opera's flaws: the unforgiving nature of the story, the overwhelming unhappiness of its characters, the difficulty of transforming a television piece to the stage. Instead he sees these aspects as pluses.

"It's a very hard-hitting piece," he tells me before the final performance at Snape. "But I don't think anyone comes to a Britten opera expecting a soft-core version of La bohème. This piece is Britten at his most angry, passionate, lyrical, dark, wonderful. It's a very strong evening in the theatre."

I ask about the challenges of setting television opera on the stage. "What ought to be a problem turns out to be a great strength," he says. "There are jump cuts and cross-fades in the space of a bar of music. In 1970 these tricks would have been odd and unconventional on stage, but now they're what we expect from theatre. In my very first pieces back in the 1980s (when Bartlett was director of the experimental Theatre de Complicite) we worked a lot with the idea of two scenes happening at once or showing the audience the mechanics of a scene change. All that is meat and drink to me."

Britten was apparently suspicious of composing for television. He didn't have one himself and didn't care for the medium, yet Bartlett's production makes the work's dramatic tension absolutely convincing; not for a moment do technicalities get in the way.

That the characters' faces would have been shown in up-close screen shots perhaps encouraged Britten to pursue new depths of psychological territory. "In some ways this is his most interior piece," says Bartlett. "You can write the plot on the back on an envelope: a young man says 'I don't want to be a soldier'; his family says 'you've got to be'. The action of the opera is inside people's minds and inside their hearts."

Such intense introversion marks the start of Britten's late period. The final 20 minutes of the opera point to the uncompromising interior world of his last opera, Death in Venice.

Bartlett vehemently refutes what he calls "received opinion" that the characters in Owen Wingrave are simplistic. "You'll hear the view that the women are unattractively stubborn. Excuse me? That is plain old-fashioned sexism.

"Think of the three women at the heart of the opera: one lost her fiance, one lost her father, one lost her husband. They are incarcerated in an impoverished English country house run by a man just on the edge of sanity who is dying. These are tough women, and they are going to fight tooth and nail not to have their lives thrown away by one impetuous young man's idealistic and rather naïve politics. They are extraordinary characters, very powerfully written right from the inside."

After watching the performance in Aldeburgh I agree with Bartlett. What is most telling is how much sympathy he displays for all of the characters in an opera that has been criticised as overly black and white. "If you just read the synopsis," he says, "you would think that there's a good guy, Owen, and that his family are all bad guys. Actually it's the other way around. The violent person, the difficult person, the obtuse person, is Owen.

"This is a very complex picture of the way in which violence within the family grips everyone and nobody can think of a way out.

"There's a marvellous line at the end of the first act when Mr Coyle, who is training Owen to go to Sandhurst, says: 'All my life I have taught the art of war but for war in the family there is no answer in the books.' Wingrave is called the pacifist opera but it's really an opera about violence, and violence in its most intimate form. Violence that happens across the dining table, in the drawing room, in the bedroom."

Owen Wingrave is at the King's Theatre, Edinburgh, on August 15 and 17. www.eif.co.uk