Children as young as 10 are being robbed of their childhood by pressure to copy scantily clad pop stars such as Kylie Minogue, the leader of a teaching union said yesterday.

Jim O'Neill, chairman of the Professional Association of Teachers, argued that primary school pupils were losing their innocence because they were bombarded with lewd images and exposed to inappropriate storylines and bad language on television programmes before the 9pm watershed.

Mr O'Neill, a former headteacher from Leicestershire, told the union's annual conference in Harrogate that Margaret Hodge, the minister for Children, should force television stations to stop showing programmes with sex and bad language before the watershed.

He said the singers Kylie Minogue, Christina Aguilera and Britney Spears were a bad influence and criticised the soap opera Emmerdale for a recent storyline before 9pm featuring a lesbian relationship. He said he was concerned that the F-word was now so common on television programmes that it was losing all power to shock, and some people believed it to be a "fully acceptable part of speech".

"Childhood itself is under so much pressure today," Mr O'Neill told the conference. "Our youngsters are almost coerced into growing up far too fast and far too soon by some of the pressures and policies around them. There are pressures to succeed, to conform, to be in fashion, to be 'cool' and to have anything and everything immediately - especially if it's the designer label of the day. I know memory plays tricks but it seems to me that although my generation certainly did not have all that today's youngsters have, we were happier than they are because we still had a true childhood."

Later, Mr O'Neill said that there were increasing reports of primary school children going to school dressed in unsuitably short skirts and G-string underwear in an attempt to mimic pop stars.

He said he had every sympathy with Anna Roxburgh, headteacher of Hamp Community Primary School in Bridgwater, Somerset, who in May banned her pupils from wearing G-strings to school.

"I am concerned about the images in magazines of pop stars who are virtually wearing nothing," he said. "This is putting pressure on children to dress this way.

"You see Year 6 girls where you wonder sometimes at some of the outfits they wear whether the parents have vetted what their children were wearing that morning."

Margaret Morrissey, of the National Confederation of Parent Teacher Associations, said that concerns about individual pop stars were just part of the problem. She said the Government, advertisers and marketing companies had to reach an agreement to try to keep children as children and not to cash in on the commercialisation of clothes and make-up and hairdressing. "We have been saying for a long time that many of the magazines that are targeted at 10 to 12-year-olds are really highly suggestive and a major part of the problem."

* The Government hopes the footballer David Beckham's decision to take Spanish lessons will encourage more teenagers to sign up for Spanish GCSE, Stephen Twigg, an Education minister, told the conference in Harrogate yesterday