|PIC1|Amazing Grace, a film about William Wilberforce's political fight to end the British slave trade, has been criticised for "writing blacks out of history".

But its director, Michael Apted, said he deliberately focused on one Englishman's political battle.

Black leaders have accused the film of "prettifying" the slave trade, making Wilberforce the abolition movement's sole champion and ignoring the role slaves played in their own emancipation.

Amazing Grace opens 23 March and stars Ioan Gruffudd as William Wilberforce, who fought to have the slave trade banned by parliament and finally saw success when the legislation was passed in 1807.

Lola Young, a black member of the House of Lords, wrote: "It is important ... to recognise how easy it is to come to the view that some lives are more important than others and for us to be complicit in perpetuating new varieties of discrimination."

But director Apted said that he deliberately wanted to focus on the political side of the slave trade.

"There are a lot of films to be made about slave trade, and this is one of them," Apted told Christian Today. "The whole genesis of this film was the political aspect of the film and the anti-abolitionist aspect of the film.

"This was one battle, this was a parliamentary battle," he said at the British premiere of the film late on Monday.

"But it was a major step forward because it started the whole thing in process and my film was always going to be about the political angle," he told Reuters.

"It's not about the plantations, it's not about the high seas. There are other works, other films about that. It is a fresh and unique look at what was going on in the political world ... and that's what I focused on."

Apted also wanted to show that politicians, for all the bad press they get, can make a difference for the better.

"I've always been looking to try and do something positive and to show that politicians can be occasionally heroic and do good things, and this is a good illustration of that."

Amazing Grace, already released in the US last month, is one of a series of events in Britain this year marking the bicentenary of the abolition of the slave trade, including postage stamps, exhibitions and memorial services.

The debate surrounding the film reflects a broader discussion about people's perceptions of slavery and why it's lessons are still relevant today.