A young woman was lucky to escape unhurt when a missile was thrown at her car from a motorway bridge.

The woman, in her 20s and from Maidstone, was driving under a bridge over the M20 when the object was lobbed at her car.

The windscreen of her Toyota Rav4 was shattered in an attack branded "irresponsible and malicious" by police.

It happened on the London-bound carriageway near junction three for West Malling at about 6.45pm on Saturday.

Police are appealing for witnesses to come forward. Detectives do not know what object was thrown from the bridge.

Insp Nick Sparkes, from Kent Police, said: "This could have quite easily smashed the windscreen and struck the driver with disastrous consequences.

"There have been incidents of this kind in before and I cannot emphasise strongly enough that on this occasion the driver was lucky.

"Throwing anything at a moving vehicle is irresponsible and malicious, but to throw something large from a bridge at a moving vehicle could kill someone. I encourage anyone with information about this to contact the police."

In July 2010, Michael Baker, died after the recovery truck he was in collided with a lorry.

Police believe the 47-year-old, from Littlehampton, had stopped because a group of children were throwing stones from a bridge shortly before the two vehicles collided on the A20 near the Swanley interchange in July 2010.

A 10-year-old boy was arrested over the incident but never charged. The police investigation continues.

Witnesses to the latest incident are asked to phone Kent Police on 101 or Kent Crimestoppers, anonymously, on 0800 555 111.