Robert Whitfield and Deng Lual, both 14, have been missing since Monday morning when they ran into the bush land east of the Airds area about 11.40am.

One of the boys contacted his mother about 8.50pm and told her they were lost.

Police used mobile phone tracking to narrow the area down to near Keith Longhurst Reserve off Georges River Gorge at Kentlyn.

But after large-scale searches on Monday, Tuesday and Wednesday, involving police, paramedics, the SES and Rural Fire Service, the boys still haven't been found.

Police said the boys ran into the bush after leading police on a car chase from Bradbury to Airds.

The pair were travelling in a black BMW, which was abandoned at a reserve off Banooke Way.

"Despite the searches, police have been unable to locate the boys, and are renewing their appeal for information about their whereabouts," police said.

Pictures of the two boys have now been released.

Robert is described as being of Aboriginal/Torres Strait Island appearance and 150cm tall. He has a thin build, short brown shaved hair and brown eyes.

Deng Lual is described as being of African appearance with a dark complexion. He is 155 to 160cm tall with a thin build, short dark hair and brown eyes.

Anyone with information should contact Crime Stoppers on 1800 333 000.