They travelled to Sri Lanka as part of a campaign by Unicef and the World Health Organisation to eradicate polio worldwide by 2000.

The pair joined a Unicef delegation on Saturday to tour refugee camps and helped give children oral vaccination against the disease.

Rock veteran Dury and former Take That heart-throb Williams had planned to visit the northern town of Jaffna - but were diverted to Vavuniya by UN officials following a bomb explosion in Jaffna a week before their arrival.

Let me immunize you: Robbie Williams in Vavuniya

Tamil Tiger rebels - fighting for an independent homeland for minority Tamils - and government troops both laid down their arms for "days of tranquillity" on Friday and Saturday, so the immunisation programme could take place.

Williams said: "The thing that had the most impact for me was all the smiling in the face of adversity - not the state that they live in but how they are looking for the best. I've had the best five minutes of my life playing with those children."

Dury, himself a polio sufferer, said: "The most important thing for me is seeing Unicef working by coming out here and it makes me tempted to go back and yell it out loud."

Unicef officials are confident the programme, which is into its fourth year, is proving to be a success.

"We have a regular programme of immunisation where already 80% of children are immunised, but this particular national immunisation day is to eradicate polio," said Unicef programme officer Hiranthi Wijemanne.

"From 1993 we haven't had a single case of confirmed polio. Sri Lanka is on the threshold of eradicating polio and we have a good chance to do so in the new millennium," she added.

Dury, best known for hits like Hit Me With Your Rhythm Stick, took part in the campaign last year, while this is the first time Williams has helped Unicef.