The family of the "milk carton kids" who have been missing for 25 years have begun digging up a field after receiving a "credible" new tip off.

Schoolboys David Spencer, 13, and Patrick Warren were out playing in Chelmsley Wood, Birmingham, when they vanished on Boxing Day, 1996.

The bodies of the pair – whose faces and a call for information appeared on milk containers – have never been found.

This week, David’s brother Lee O’Toole, 34, who was nine when his sibling disappeared, started leading a dig on land off Damson Wood Lane, near Solihull Moors FC, West Midlands.

Hundreds of volunteers started helping on Monday following "credible" new information from the Channel 4 documentary In the Footsteps of Killers, which claimed that the child-killer Brian Field had been seen with the boys in the days before they vanished.

Mr O’Toole said: "The community is doing what the police should do. A man contacted me directly to say he had seen a man digging in a field off Damson Wood Lane, near Solihull Moors Football Club, at the time they disappeared.

"Apparently he’s been telling the police for years and they’ve never acted on it.

"I don’t know what more police need. They’ve left me no choice other than to put the shovel in the ground."

West Midlands Police, who are still investigating the boys’ disappearance, have urged volunteers to stay away from the unofficial dig site.

A force spokesperson said: "We recognise and sympathise with the strong sense of feeling surrounding the disappearance of Patrick Warren and David Spencer in 1996.

"It’s highly emotive for their families, friends and the wider community.

"We understand there are many frustrations and a lack of trust around our initial investigation and the many reviews we’ve carried out since.

"We also know a group has been set up encouraging people to take matters into their own hands and dig at the back of a football ground in Damson Wood Lane.

"We’d urge people not to do this. Searching should be left to us and is based on areas of interest, we use trained specialist experts who are able to preserve any evidence that may be found.

"We’re in touch with the Spencer family, and others, who are providing new information."

Following a review of the case in 2006, convicted murderer and paedophile Field was interviewed by cops in connection with the case, but he denied any involvement and was never charged.