Mr Smith, who attended the gathering in the most exclusive conference hotel, insisted the reports were "complete nonsense".

He said: "There was certainly no booing. I and a number of others chatted with teachers and pupils very happily afterwards."

But the headmistress at the £10,000-a-year Talbot Heath school immediately claimed Mr Smith had got the facts wrong.

"The band was definitely booed. We had only been drinking orange juice so I don't think there's any possibility we might have got things wrong," she said.

The conflicting accounts are the latest fall-out from an embarrassing incident immediately seized on by Labour's opponents.

The Conservatives have accused Labour of "class envy" after party activists booed music pupils from a private school at a conference fringe meeting in Bournemouth.

Michael Ancram: Demanded an apology by Labour

Tory Party chairman Michael Ancram demanded an apology from Tony Blair following the "despicable" incident, which happened just hours before the prime minister declared the end of the "class war" in his conference speech.

The pupils from the Bournemouth school, aged 14 to 16, had played jazz to the gathering aimed at highlighting social exclusion, on Monday night.

Richard Robinson, Deputy Head of Talbot Heath, said at the time: "They were applauded for their playing and Bournemouth got a cheer, but when they said they were from a private school there was a boo.

"The girls were surprised and a little disappointed - it's not the normal reaction."

But Mr Robinson said the pupils had been "philosophical about it".

Mr Ancram said it was "a display of mean-minded socialism at its very worst."

He said: "It is the mentality of the schoolyard bully.

"It is a disgrace that Tony Blair allows his party members to vent their class envy on 14-year-old schoolgirls.