A veteran radio presenter who had been hailed by his radio station for "verbally assaulting callers" was sacked today after breaking strict broadcasting impartiality rules.

James Whale, touted by talkSPORT as having a confrontational style that would "have Attila the Hun running for the hills", had used his night-time show on March 20 to call for Londoners to vote for Boris Johnson in Thursday's mayoral poll.

The 56-year-old, who worked for the company for 13 years, was sacked after bosses termed the move a "gross error of judgment" which had broken Ofcom rules. The regulator had been investigating complaints made after the show.

"It’s very unfortunate. We have investigated the matter and after serious consideration, the station reached the decision that there was a clear breach of the rules and that we had no choice but to terminate his contract," talkSPORT said, in a statement.

"James Whale is guilty of a gross error of judgment which we found to be totally unacceptable.

"TalkSPORT has acknowledged the seriousness of the complaints received, does not excuse the content of the broadcast, and has told Ofcom that it has taken steps to prevent this happening again.

"The matter is still under investigation by Ofcom so it would be inappropriate to comment any further on the details of the complaints."

By this afternoon, talkSPORT had already removed any reference to Whale's show from their website. His picture had been replaced by that of Tom Rivers, another presenter.

A profile of the 56-year-old presenter, which remained on the site, hailed his ability to "offend" people.

"You know you are in the presence of someone special when you look at the number of people James Whale has managed to offend over the years," it said. "Whether you’re pushing 80 or still collecting My Little Pony, if you annoy Whale, he’ll soon let you know about it."

It added: "The outspoken and self-righteous late night king has developed a cult following over the years with his confrontational style that would have Attila the Hun running for the hills.

"James loves nothing more than verbally assaulting callers on his late night phone-ins and it seems people on the other end of the line can’t get enough as we’ve gone through eight switchboards in the last two years."

Whale's agent Stuart Hobday told the BBC that Whale was "deeply disappointed" with the decision.

"He’s spent 13 happy years at TalkSPORT," he said. "He’s saddened at the way this has happened and it’s come as a huge shock."

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010