The broadcaster was suspended by the BBC when the drug allegations were published in the News of the World in April this year.

But following the imposition of the penalty at Horseferry Road Magistrates Court in central London on Wednesday, the corporation said: "The BBC is adamant that it does not tolerate the use of illegal drugs.

"However, the BBC Radio management is impressed by the way Johnnie has handled this crisis in his life and has sought professional treatment.

"Radio 2 has also listened to Johnnie's audience who registered an overwhelming amount of support for him."

In addition to his fine, Walker was ordered to pay �200 costs.

Pressure

The court heard that Walker had turned to cocaine while facing pressure at work, the loss of both his parents in close succession and the end of a long-term relationship.

Reporters, claiming to be interested in setting up a new radio station, had arranged a meeting with Walker at the Grosvenor Park Hotel in central London.

Magistrate Rosmond Keating criticised the methods of the journalists who approached Walker and the "filth" they had written about him.

But she told the 54-year-old he had a duty to maintain higher standards of life than other people because of his position as a celebrity.

However, she noted that he had sought help for his addiction and said: "I hope some good will come out of this appalling incident."

Regret

Outside court Walker, of Leigh, Wiltshire, thanked his family and listeners for their support, saying they had been "a great source of strength".

The DJ said he was "extremely sorry" for the embarrassment he had caused to family, friends and the BBC.

He said: "I am trying my very best to put my troubles behind me on a daily basis."

In court Walker's counsel, Antony Chinn, said of his client: "He found himself alone and working hard and he turned to the occasional use of cocaine.

"But what started off as a crutch or a friend soon turned into an enemy. It is a very addictive drug."

He said Walker had been considering getting help even before he was exposed.