There are a great many dangers in trying to fictionalise a horrific event like the massacre of 24 Iraqis by a unit of US Marines, one of whose vehicles was hit by a roadside bomb at Haditha in November, 2005. But Nick Broomfield, who bows more to Gillo Pontecorvo's classic Battle of Algiers than to any of the recent American films about the Iraq war, has succeeded in avoiding most of them.

Shooting not in Iraq but in Jordan, he uses in his cast many ex-Marines who served in Iraq, and allows them to improvise much of the dialogue. The other actors, who include the two men who plant the bomb and the nearby families who witness the planting and the explosion and are thus suspected of colluding, are Iraqi.

He makes neither villains nor heroes of any of them. Even the Sunni bombers, persuaded by merciless insurgents to do their work for them, are seen to have doubts about the result of their actions. If they don't co-operate, they are killed. If they do, they have to kill without compunction. And the innocent families know that to give them away to the Americans would mean their death, too.

The guilty Marines, one of whom says with some justice that "we're just live bait", are depicted as young men from the American sticks who lose their nerve when the bomb explodes, killing one of their men and wounding two more. They go on a furious rampage of revenge, but they, too, are victims, forced to respond under extreme stress and in the way they have been trained.

The film's one polemical stance is to compare the American officers at headquarters - who at first sanctioned what the Marines did and lied about it before the press blew their cover - with the religious figures who saw in the bombing and its aftermath a propaganda coup against the occupying forces. To them, the dead were merely martyrs in a worthy cause.

We do not know the whole truth about the massacre, and perhaps we never will, since the court case is befuddled with contradictory evidence. But the film seems pretty near to it, and was researched with some thoroughness.

It is not a comfortable watch. But it is an impressive one, and makes a more humane and balanced document of the war than Brian De Palma's much praised and equally reviled Redacted.

This is as well structured and shot as any film Broomfield has given us, looking as much like a documentary as many of them but freely admitting that it is a fictionalised version of the truth. Terrible things happen in war, and that is what Battle for Haditha tells us in the plainest of terms, but never with too melodramatic an effect.