The man on the left has a contract with Nike worth pounds 2m. The worke rs who make his shoes get pounds 40 a month

Training shoes which are endorsed by some of the most glamorous names in sport, for contracts worth millions of pounds, are often made by Asian workers who are paid as little as 2.5p a pair, according to a report on the sports-shop industry published today by the charity Christian Aid.

The shoes, advertised by the likes of footballer Ryan Giggs and athlete Linford Christie, are sold for about pounds 50 a pair in British shops. The average labour costs for producing each pair of shoes, including wages and other social costs, are 46p in China, pounds 1.08 in the Philippines and pounds 1.19 in Thailand.

According to Christian Aid, the head of Nike, Phil Knight, earned pounds 929,113 in 1994. A woman worker producing Nike trainers in China, one of the fastest- growing manufacturers, would have to work nine hours a day, six days a week for 15 centuries, on current wages, to match such a salary.

The report focuses on the five biggest names in the British sports shoe market - Reebok, Nike, Puma, Adidas and Hi-Tec. Last year, these companies manufactured pounds 27m worth of sports trainers for the British market, employing through sub-contractors in Asia.

The report says: "As the sales pressure mounts to buy the latest trainers this Christmas, it's time the companies producing them came under pressure to improve pay and conditions."

It continues: "The pounds 25m deal with Reebok reputedly lined up by Liverpool Football Club recently would more than double the wages of the 40,000 workers who make Reebok trainers in China and the Philippines."

Ryan Giggs has a contract worth about pounds 1.5m with Reebok, and his Manchester United colleague Eric Cantona's contract with Nike is thought to be worth more than pounds 2m. Paul Gascoigne was reportedly recently paid pounds 2m by Adidas to wear its boots. He refused to comment on the report.

However, at least one leading British sports figure has said they would have accepted lower sponsorship deals if they had been aware of the exploitation of workers. Lisa Opie, the former British squash champion who was sponsored by Reebok for six years, said: "When you see the amount of money given to some of the top stars, it's ridiculous ... but the sports-shoe companies are competing to get the big names."

Nearly all workers in the Asia factories are single women, which means subcontractors can avoid paying maternity benefits. In Thailand, 85 per cent of the workforce is female. The average age is 22.

Christian Aid has called for meetings with all the sports- shoe companies. "We are urging the companies to pay higher wages, enforce codes of practice, and improve factory conditions," said Peter Madden, one of the writers of the report. "As a result we might see one advertisement fewer a week, or a sports personality may receive a few thousand pounds less, but is this such a big price to pay?"

The big sports-shoe companies this weekend defended their human rights record and argued they had introduced codes of conduct to protect the workers of their subcontractors. Reebok will present its annual human rights award in New York this evening; last year it went to a boy who campaigned for the rights of child carpet-makers in Pakistan.

"In the past few years we've implemented extensive programmes for monitoring and auditing workplace conditions, and we ... take a very careful look at our business partners, and the workplace conditions they have," said Doug Cahn, head of human rights for Reebok International.

A spokesman for Puma UK said the company was "very big on health and safety". He added: "I can't believe we would exploit people."

The Independent was unable to contact the other three companies.