The man was arrested immediately after the incident by gardai from Donnybrook, but was later released without charge.

The interruption occurred in the opening minutes of the show, just after Kenny had welcomed his first guests . . . the judges of You're a Star . . . to the programme. A member of the public, wearing a brown leather jacket, approached Kenny and accused him of being "a censor", going on to say that Kenny and Gay Byrne were "insufferable arseholes". Kenny was heard to say "Thank you very much", before the production team cut immediately to a commercial break.

As soon as the show was off-air, the man was surrounded by RTE security personnel. According to You're a Star judge Linda Martin, who was sitting just feet away from Kenny, the man became more agitated when the security guards arrived.

"His language became even more coarse, and he was telling them not to touch him, " she said yesterday. "At first we had thought that it was a prank, and that he'd been brought in to have a go at Brendan [O'Connor]. But then we realised that he was serious, and I kept watching his hands.

I thought to myself that he was going to produce a gun or a knife of some sort. But full credit to Pat Kenny, he remained very calm during the entire thing, and that helped everyone else to stay calm too."

The man was eventually grabbed by RTE security guards and taken into custody by gardai from Donnybrook. A spokeswoman for RTE yesterday said that the man was a member of the public, but that she could not reveal whether he had gained access to the studio as a member of the Late Late Show audience, or by some other means.

"In regard to security measures within RTE, these are under constant review but, specifically for security reasons, we do not give details of such, " she said. "RTE is making no further statement on the matter while it is still being investigated."