Mike Leigh is known for crafting gritty dramas

The fictional film, called Vera Drake, follows the life of a backstreet abortionist in 1950s London.

The heroine Vera, played by Imelda Staunton, visits girls' homes to carry out secret operations at a time when abortion was illegal in Britain.

Leigh says he hopes the film will "pose a moral dilemma" for the audience.

Vera, played by Shakespeare in Love actress Imelda Staunton, is eventually found out and prosecuted for her crimes.

Launching the film in Venice, Leigh said abortion is an issue that excites huge numbers of people across the world.

'Absolute monster'

He said: "I felt very strongly it was time to deal with it directly in a way I hope poses a moral dilemma for the audience and doesn't draw simple black and white conclusions.

"You have to consider whether this woman, and these women she helps, are innocent or not."

Leigh said it is possible to conclude that Vera is "an absolute monster" but equally possible to think she is "motivated by wanting to do good for people."

Staunton, whose performance has been warmly received, believes "she absolutely thinks she is doing the best for these woman and gives no judgement".

Leigh hopes the film will open a moral debate in the country.

He says the film shows how working class women were forced to resort to backstreet abortions.

But the rich exploited a loophole allowing them to have the procedure provided a psychiatrist vouched that their mental health was at risk if they went ahead with the pregnancy.

"In many parts of the world that remains the case and it is a massive problem that is very difficult to solve," Leigh said.

The film, which also features Jim Broadbent, is in competition for the Golden Lion prize at this year's festival.