'Electric fence and dog patrols' for palace

Buckingham Palace could be ringed by electric fences and patrolled by police dogs and armed guards in a security clampdown after the Batman protest.

This should mean new measures to protect the perimeters of sites such as the palace and Windsor Castle.

Until now authorities have allowed a balance between protection of the royals and a desire not to turn buildings into fortresses.

Scotland Yard also wants to take complete control of security at royal sites. At present responsibility is split between police and security services.

One senior police source said: "We have to go back to the drawing board. We have to make sure this does not happen again and that means securing the perimeter. We will look at everything, including electric fences, dogs inside and patrolling the fence.

"There will need to be a radical change in the way the royals think about security."

The development came as London's top policeman called for trespassing on royal premises to be made a crime.

Metropolitan Police Commissioner Sir John Stevens also warned that if anyone tried to emulate the stunt by fathers' rights group Fathers 4 Justice, they risked being shot. He said it was "unacceptable" for officers to be put in the position of having to decide instantly whether an intruder was a protester or a terrorist.

"The officers showed professionalism and good judgment in coming to the right decision," he said. "I would not want anyone injured or killed in the future because of someone-taking a chance too far." New legislation creating a "royal trespass " law was recommended by the Armstrong report after a security breach at Windsor Castle last June.

Sir John said he was confident Home Secretary David Blunkett would introduce a law as swiftly as possible.

A report on Monday's security fiasco has highlighted how Fathers 4 Justice protesters identified a weak spot in the palace perimeter. They were able to sprint across a grass area and erect an extendable ladder.

Once Batman protester Jason Hatch got onto the building there was little police could do. But his colleague Robin - David Pyke, 48, was challenged by armed officers as he climbed the ladder. According to sources, he came perilously close to being shot.

Mr Hatch, 32, was released on police bail yesterday after he was arrested on suspicion of criminal damage in connection with the stunt. The campaigner from Cheltenham was told to return to a London police station in December but is unlikely to face charges.

His protest reportedly caused his girlfriend Gemma Polson to dump him after she became fed up of his publicityseeking antics. "It was going too far. Fathers 4 Justice has taken over his life," she said.

Mr Hatch was brought to ground in a cherrypicker on Monday evening after spending the afternoon precariously balanced on a narrow ledge.