The BBC has been fined £150,000 over the "grossly offensive" prank telephone calls made to Fawlty Towers actor Andrew Sachs on one of its radio shows.

TV host Jonathan Ross and comedian Russell Brand left lewd messages on Sachs' mobile phone during a show last October, leading to a public outcry and more than 40,000 complaints.

Watchdog Ofcom said in a statement it had levied the fine because of the "extraordinary nature and seriousness of the BBC' failures".

It said there had been a lack of editorial control and BBC managers had wrongly given Brand and his team too much responsibility for the show's output.

"The presenter's interests had been given greater priority than the BBC's responsibility to avoid unwarranted infringements of privacy and minimise the risk of harm and offence and to maintain
generally accepted standards," Ofcom said.

During the show, the presenters joked that Brand had slept with Georgina Baillie, the 23-year-old granddaughter of Sachs. Sachs is best known for his role as Spanish waiter Manuel in the classic 1970s comedy show.

Amid a growing furore, Brand and the head of Radio 2 quit, while the BBC suspended Ross, one of its highest paid employees, for 12 weeks. He has since returned to his job.

The BBC's supervisory body said the prank calls were "grossly offensive" but that the corporation's response had been correct.

"As we said last October, this material should never have been broadcast and we apologised unreservedly for that," a BBC spokesman said.

"The BBC has since taken comprehensive action to deal with what were unacceptable failures in editorial judgement and compliance which led to the broadcast.

"In addition and as is well-known, two very senior managers and Russell Brand resigned and Jonathan Ross was suspended without pay for twelve weeks."

The affair was one of a series of embarrassing scandals to shame the publicly-funded broadcaster in recent years, leading to questions about its role and how it should be funded.

In 2003, its coverage was strongly criticised by the government after the broadcaster suggested the case for war in Iraq had been "sexed up". An inquiry sided with the government.

It has also been fined for running unfair or rigged competitions, and had to apologise to the Queen after it wrongly implied in a documentary trailer that she had stormed out of a photo-shoot.