The BBC on Wednesday indefinitely suspended two of its most popular broadcasters, Russell Brand and Jonathan Ross, for leaving a series of lewd phone messages on an actor's answering machine.

The prank calls to 78-year-old actor Andrew Sachs, played on state-funded BBC radio, have sparked condemnation in Parliament and an investigation by Britain's media regulator.

The calls were broadcast Oct. 18 on Brand's national radio show and have drawn more than 18,000 complaints. In the messages Ross jokingly claimed Brand had slept with the granddaughter of Sachs, best known for playing Spanish waiter Manuel in 1970s sitcom "Fawlty Towers."

Brand and Ross have apologized, but even Prime Minister Gordon Brown was among those who said the calls were unacceptable.

On Wednesday the BBC's director general said the pair would be suspended until an investigation was complete.

BBC chief Mark Thompson said he was making a "personal and unreserved apology" for the "completely unacceptable broadcast."

"BBC audiences accept that, in comedy, performers attempt to push the line of taste. However, this is not a marginal case," he said.

"I have decided that it is not appropriate for either Russell Brand or Jonathan Ross to continue broadcasting on the BBC until I have seen the full report of the actions of all concerned."

Ross, 47, and Brand, 33, also have apologized for the calls. But several politicians have called on the BBC to fire the pair, who are among the network's most popular broadcasters.

Brand has a burgeoning U.S. profile thanks to film appearances and a job hosting last month's MTV Video Music Awards. He offended some viewers of the awards show by mocking clean-cut pop act the Jonas Brothers and referring to President George W. Bush as "that retarded cowboy fellow."

Ross hosts a TV talk show, a movie-review program and a weekend radio program. He is one of the BBC's highest-paid personalities. Last year he signed multi-year-multimillion-pound (-dollar) deal with the broadcaster.

Brown said the BBC and regulators had to decide what action to take. "This is clearly inappropriate and unacceptable behavior," the prime minister said Tuesday.

Telecommunications regulator Ofcom said it would investigate whether the calls breached the broadcasting code, which sets standards for fairness and privacy.