Why Alan Jones has been forced off air

Top rating radio broadcaster Alan Jones is in hospital and off air indefinitely as he seeks treatment for severe back pain.

"There are no more places left to inject me now," the 77-year-old joked from his bed in St Vincent's Hospital yesterday.

He was off air for four months after surgery on his back and neck two years ago but fought back with exercise and pilates.

"I hope it is not as bad as all that," he said before another battery of tests.

"There is a reason for this but they cannot find that out."

His 2GB fill-in Chris Smith told listeners yesterday: "He's currently in hospital being treated for severe back pain. His doctors are working to establish exactly what the problem is. The end result is he'll be back as soon as he can but we're not sure exactly when."

Despite a 1.5 per cent drop in the latest ratings, Jones remains king of Sydney radio with yesterday's results showing he has a 17.5 per cent share of the market.

His station 2GB remains comfortably ahead of its competitors with a 14.1 per cent market share.

But the broadcaster has been caught up in a string of controversies.

His interview with Opera House boss Louise Herron over her resistance to showing images of The Everest on the sails of the iconic building attracted criticism.

Just last month, Jones caused controversy after speaking to Opera House boss about her refusal to project images of The Everest onto the sails. Picture: AAP Image/Brendan Esposito

Hundreds of protesters turned out and some put the blame on Jones. Picture: Mark Metcalfe/Getty Images

Fairfax-owned Macquarie Media, which owns 2GB, told the annual general meeting last week that it dealt with Jones directly following the interview.

The station was also ordered to pay Queensland's biggest-ever defamation payout of $3.75 million to the Wagner family for Jones's comments on their involvement in the 2011 Lockyer Valley floods.

The payout is insured but Macquarie Media chairman Russell Tate has refused to comment on whether Jones will be asked to contribute.

JFellow colleague Ben Fordham said they needed him back on air. Picture: Lawrence Pinder

Mr Tate told the AGM there were "new procedures and new rules" in place as a result of the case.

Mediaweek editor James Manning said the controversies would not affect the broadcaster's position.

"There's not a chance in hell Macquarie would ever drop Alan Jones," he said.

"He's the driving force of the station and has topped every ratings survey for decades."

Ben Fordham, 2GB drive host, said: "Alan has more backbone than anyone I know, so I am sure he is going to make a full recovery. We need him back on the air."