Veteran broadcaster Jonathan Dimbleby has admitted that he tried cocaine once and called on middle-class people dabbling in drugs to think again about the misery they are causing in south America.

The host of long-running BBC Radio 4 show Any Questions? said he has a "contempt for cocaine sniffers in this country who are intelligent middle-class people but do not realise that they are fuelling a drugs war that is leading to misery for millions".

He revealed he took the drug when he was in his early 20s and also tried marijuana but did not enjoy either.

"I had cannabis twice in my early 20s. And once, in America [at around the same age], I did a line of cocaine. I sneezed it all over the place much to the dismay of people around who saw it as this precious substance," Dimbleby said. "It tickled my nose, and then it blocked my nose. And I had no experience from it at all."

Dimbleby, 67, made his remarks in an interview with the Daily Telegraphto publicise his new BBC2 series A South American Journey with Jonathan Dimbleby.

He was shocked by the effects of the cocaine trade in Colombia. "By our criminalising the use of cocaine, of people stuffing their noses with coke, we are causing mayhem to the lives of millions of people in South America," he said.

He did not go as far as calling for the decriminalisation of the drug but said "we should take the matter more seriously".

He added: "I think the criminalisation of drugs globally has produced far greater trouble for everyone than it if were not criminal."

He said it was "ridiculous" to attack public figures such as politicians for having taken drugs when they were at university.

"I think it is ridiculous to lay into adults who happen to have responsibility on the basis of what they did or didn't do at university," Dimbleby said.