Black newspaper The Voice reported the Lethal Weapon star was too busy to take the part of Stephen's father Neville, in the drama about the 18-year-old's murder and the resulting campaign for justice.

Stephen was fatally stabbed by a gang of white youths at a bus stop in Eltham, South London, in April 1993.

Stephen Lawrence: Murdered at a South London bus stop in 1993

The drama, being produced by Granada Television, will start with scenes of the murder and will then follow events in the years afterwards, including the inquest into his death, the failed private prosecutions brought by the family against the suspects, and the recent judicial inquiry.

Marianne Jean-Baptiste is strongly tipped to take the role of his wife Doreen. She was nominated for an Oscar for her part in Mike Leigh's Secrets And Lies.

A supporter of the family, Ros Howells, hopes the film will give an insight into the strains placed on the Lawrences since the murder.

She said: "We always have to remember the Lawrences were perhaps among the most ordinary black people. They weren't campaigners, they weren't people involved in any struggle.

"To be thrust into the limelight in the way that they have been and to also deal with grief is very difficult.

"They have become celebrities. They had really chosen to mind their own business, quietly bringing up their children. Suddenly they found themselves shaking the pillars of British society."

Granada TV: Line-up still to be finalised

She hopes the film will also dispel some myths and help the family cope with the aftermath of Stephen's death.

"Hopefully this film will not only be therapeutic for the family but it will also contain lessons for others.

"Everyone expects you to peform in the way you did before this happened. Everyone has changed, you cannot ever switch off. Don't let anybody ever tell you that trouble brings people closer together."

A spokesperson for Granada declined to comment on the casting for the film, as the full line-up had not yet been confirmed.

The company has a long-standing reputation for tackling current issues through drama. In 1990 Who Bombed Birmingham? led to public pressure wrongfully convicted of the IRA terror attack on a pub in Guildford 15 years earlier.

Jimmy McGovern's Hillsborough drama raised questions about the role of the South Yorkshire police force in the 1989 football disaster.

But the spokesperson added: "It's not the intention to make a political statement but to investigate on a personal level the destruction Stephen's murder did to the Lawrence family, and the effect on them of losing a son."