The mother of murdered teenager Stephen Lawrence has said it is "unbelievable" that inquiries into the aftermath of her son's death are still ongoing after nearly 26 years.

Stephen was murdered by a gang of up to six racist attackers as he waited for a bus in Eltham, in 1993.

Now, a public inquiry into undercover policing, which has been beset by delays, is looking at claims that grieving families were spied on as they campaigned for justice, including the Lawrences.

Giving evidence to the home affairs select committee on Tuesday, Baroness Lawrence accused the Met Police of trying to avoid giving the "true facts" of what undercover officers did to the inquiry.

She said: "The undercover inquiry that's happening now, the police are doing all that they can not to give the true facts of what happened."

The peer also claimed that chairman Sir John Mitting has not appreciated the lengths an officer would go to in order to keep their activity secret.

"I don't think he understands the level of what a police officer would go through in order to deny and to secret whatever it is that they're doing," she said.

"This has been going on for three years now and he still hasn't taken evidence. They're still going through the paperwork.

"For me 25 years, coming up to 26 years, and this to be still going on, is unbelievable that any family should have to go through this."

Baroness Lawrence was called to give evidence on progress in the 20 years since the publication of the Macpherson report into the aftermath of her son's death.

The bungled original investigation into his death sparked outrage amid claims of racism and corruption in the police.

A public inquiry was set up four years later and in 1999 the damning Macpherson report was published, accusing Scotland Yard of institutional racism.