Broadcaster Alan Jones.

Under siege ... Alan Jones. Photo: Andrew Meares

Merecedes-Benz Australia has joined the list of companies to withdraw all advertising and marketing associated with controversial 2GB radio host Alan Jones following the shock jock's comments about the death of the Julia Gillard's father.

The German luxury car maker and its network of NSW dealers is believed to spend hundreds of thousands of dollars each year advertising with 2GB, which is part-owned by Jones.

Earlier, financial services Group Challenger cancelled its advertising relationship with Alan Jones's Sydney radio program. Challenger has advertised with the Alan Jones program since February 2011. A spokesman for the company said the demographics of Jones's audience made it a good fit.

There are calls for other advertisers and sponsors to boycott the outspoken 2GB shock jock after he said the father of Prime Minister Julia Gillard, who passed away last month, died of shame after his daughter told lies in Parliament.

Jones is alleged to have told a room of Liberal Party members: "Everyone in the Labor caucus knows Julia Gillard is a liar. The old man recently died a few weeks ago of shame. To think that he has a daughter who told lies every time she stood for parliament."

Mercedes-Benz Australia spokesman David McCarthy said the decision to withdraw all advertising was "made with immediate effect due to the inappropriate remarks made by by Alan Jones".

Mercedes-Benz and its NSW dealer network have been regular advertisers on Jones' morning program for many years.

"The message we want to send was that we don't accept the comments made by Jones," said Mr McCarthy. "This decision is for all our advertising as well as that of our dealer network."

The decision to cancel all advertising was taken by Mercedes-Benz Cars managing director Horst von Sanden this morning after a meeting with senior staff - in what was described as "a fairly brief meeting"

More than 15,000 people have signed an online petition calling for Jones to be sacked.