The parents of a schoolboy killed when he triggered an IRA bomb in Londonderry in 1973 believe Martin McGuinness knows who was involved.

Gordon Gallagher, nine, died when the device exploded in his garden in Creggan.

Northern Ireland's deputy first minister was in jail at the time, but Billy and Pat Gallagher said he could help them get to the truth about what happened.

The IRA admitted to the family that a device had been left in the garden, but claimed the detonator was added by soldiers. The schoolboy was playing cowboys and Indians in the garden with his younger brother when he tripped on the bomb.

Speaking to BBC Radio Foyle, Mr Gallagher said he was not at home at the time of the explosion, but was nearby and heard the bomb go off. He went to the hospital to be with Gordon, while his wife stayed at her mother's house with their other children.

"I went to phone Pat to say he was conscious," said Mr Gallagher. "He was wheeled past me into theatre when I was on the phone. He died at half past five. I was talking to him, I thought he was going to be all right but they said it was the loss of blood."

Mr Gallagher said IRA members came to his home to admit leaving the bomb in his garden.

"Two boys came and lied about it at the start. They told me their unit put the bomb there, but no detonator, that the Army must have come back and put a detonator - it's ridiculous. Shock or no shock, I never believed that for a second."

A Sinn Fein spokesman said Mr McGuinness was in jail at the time and had no information about the killing.

A recent report from the Historical Enquiries Team (HET) found that the IRA was solely responsible for what happened. The HET said it had failed to find any new leads in the case.