IT has survived civil wars, peasant uprising, religious rebellions and attacks from Oliver Cromwell's army.

But now Norman-built Clitheroe Castle is facing what town leaders are warning is the greatest threat in its 800 year history - a local moron invasion.

And that could lead to the castle, currently open to the public for free, being put behind a fence to keep people out all the time.

Young thugs are tearing rocks from the keep and rolling them down the 30ft embankment into the path of cars and visitors, potentially putting lives at risk. Their actions mirror a form of attack used over the centuries to protect the tower and its wealthy inhabitants from invaders.

But council bosses say the young thugs, who are taking advantage of light evenings to get into the castle grounds, have no such noble intentions, adding it is only a miracle no one has been killed by the speeding rocks landing on roads and paths around the castle.

Police and council bosses are now frantically trying to find a solution to the actions of the young thugs before someone is injured or killed. Mobile CCTV cameras are being installed in the grounds of the castle - one of the Ribble Valley's main tourist attractions - in a bid to catch the young vandals, who are also trampling flower beds, ripping up rockeries and trying to break into council-owned buildings nearby.

Council staff have been deployed to repair the rockeries and flower beds, but work on putting the rocks back into the castle walls cannot take place until specialist experts have been brought in to assess the damage.

Alan Boyer, street cleansing and grounds maintenance manager at Ribble Valley Council, said: "It is by sheer good fortune and nothing else that no one has been injured.

"It started happening a week ago and the police have been coming up here to try and catch who is doing it.

"Basically, they are ripping up rocks from the rockeries and from the castle itself and hurling them down the steep embankment. They can have no idea who is at the bottom when they throw them. They are a menace and putting lives at risk."

Coun Mary Robinson, a borough councillor and deputy mayor of Clitheroe, said: "The actions of these thugs are scandalous. The castle has survived so much over the centuries and for it to be attacked and wrecked by local youngsters is dreadful.

"It is a proud part of our history and for people to come to the town to see it and then have rocks raining on them is awful. You have to ask what the parents of youngsters involved have said to make them think it is OK to do this.

"Ultimately, the only solution might be to fence the castle off to keep them out, so people walking close to it are safe from attack. That would be dreadful, but what choice is there?"

Inspector Bob Ford of Clitheroe Police said: "The youngsters involved, and they are only a minority, are idiots. Their actions are moronic and potentially life-threatening to anyone hit by these rocks.

"We are working with the council. In the past, we have used under-cover police officers to track down and identify trouble makers when we have had problems. Those problems are minor compared to the stupidity we have now.

"By no means is it an exaggeration is suggest they could kill someone."