The castle - which was built for King Edward I between 1283 and 1287 - is described as a fine example of medieval military architecture.

Last month, its ancient walls were damaged by vandals and now, just two weeks later, officials have had to clear up after yet another break in.

This time, an exhibition housed in the chapel tower was completely destroyed.

"We are having to clear up after vandals all the time," said custodian Mike Williams.

"This is a continuing problem and something needs to be done.

"We had a gate put on the castle a couple of years ago and problem inside have been pretty quiet. But then they moved to the tower walls.

"Vandals were ripping up planks from the bridges endangering people walking along there in the morning.

"This time they've actually had to climb in to the castle, endangering their own safety to vandalise the exhibition."

Every year, the castle draws thousands of visitors but officials are worried that it will not be long before the visible signs, put them off.

Cadw - the body which protects the heritage of Wales - is now seeking urgent talks with North Wales Police and members of the local community to step up security at the castle.