Karen Tyrer, 28, of Severn Place, Cambridge, was last seen when she left a relative's house in Cambridge at about 1900 GMT on Sunday, police said.

Her white Seat Ibiza car was found on Monday parked in a lay-by on the A14 eastbound carriageway near Histon, on the outskirts of Cambridge.

The car has been taken to a police compound for forensic examination.

Ms Tyrer, who is estranged from her husband and has two children aged nine and three, is white, 5 ft 3 in and thin with dark brown shoulder-length hair.

A police spokeswoman said: "We are becoming increasingly concerned.

"We need to hear from anyone who knows anything about Karen's whereabouts or would urge Karen to contact us and let us know she is safe."