Police are appealing for witnesses after a lorry windscreen was shattered as it was being driven along a motorway.

Officers are trying to find out whether something was deliberately thrown at it.

The driver, heading towards the Channel Tunnel, had just gone under a footbridge near Junction 11a of the M20 outside Folkestone, when part of the windscreen broke.

The 29-year-old man, from Lancashire, pulled up on the hard shoulder but could not identify what had caused the damage.

The incident happened at 7pm on Wednesday.

Det Sgt Eric Norman said: "The driver said that there were no other vehicles nearby that could have thrown up a stone.

"So we are looking at other possibilities, including whether a stick or stone was thrown from the bridge. It was dark so the driver could not see anybody on the bridge.

"We want to hear from other drivers if they saw anything suspicious on that stretch of motorway.

"If we find out that his has been done deliberately we will ensure that action is taking against those responsible."

Police searched the rural area around the bridge but no-one was seen.

Anyone with information should contact Kent Police on 101 giving reference number ZY/6453.