Dr Michael Wilks, chairman of the British Medical Association's ethics committee attacked the former Health Secretary's job with British American Tobacco.

I think that everybody in the public eye who lends their name to the promotion of activity which is potentially fatal needs to consider the morality of their position

Dr Michael Wilks, BMA

Asked if he thought Mr Clarke was immoral for taking the post, he said: "Yes".

He added: "I think that everybody in the public eye who lends their name to the promotion of activity which is potentially fatal needs to consider the morality of their position."

Dr Wilks criticised Mr Clarke's business trip in the week before he announced he was standing in the leadership election.

'Grotesque spectacle'

He told the BMA's annual conference in Bournemouth, "We have had to witness the grotesque spectacle of a former Secretary of State for Health peddling cigarettes in Vietnam.

"I think it is quite despicable."

Mr Clarke appears totally unconcerned by criticism of his links to the tobacco industry.

He told the Sunday Telegraph newspaper this week: "I accept that smoking is a hazard to health, but I think adult people should be allowed to choose their own lifestyle, so long as they are properly informed.

"It's part of my rather libertarian approach to life.

"Tobacco is a proper product to sell to adults so long as adults behave courteously to other people. I am not leading people into a sin that I don't engage in."

Doctors at the BMA's conference reaffirmed their call for action to tackle the health effects of tobacco.

They unanimously voted for a Tobacco Regulatory Authority be set up to provide an adequate regulatory framework.

Tobacco companies who market their products in developing countries have been roundly criticised by health campaigners.