The Association of Teachers and Lecturers said schools were becoming dependent on the promotions run by Tesco, Walkers' crisps, Tetley tea and McVitie's biscuits.

Robin Bevan, a teacher at King Edward VI grammar school, Chelmsford, said that cash or in kind benefits from outside sources, including money raised by parents, were worth an average of £5,000 a year to each primary school - or £100m a year nationwide.

At the association's annual conference in Torquay, delegates backed calls for an independent government funded audit to establish how much schools rely on funding from elsewhere.

Angie Rutter, a special educational needs teacher at Aston Clinton primary in Buckinghamshire, said her school was well funded. But her school had a corridor crowded with dump bins for the vouchers collected by parents and children.

Often children as young as five were collecting vouchers. Parents would hand them to her in the pub if they met her out of work, she said.

"We are getting so that we are dependent. It's almost like an addiction: you do it for fun to start with and then you become dependent on it," she said.

"It is very sad that we have to rely on collecting bits of paper so we can adequately resource our school," Mrs Rutter said.

"There's a direct pressure saying, 'Eat this brand of crisps, shop at this particular supermarket, drink this brand of tea, eat this cereal and you will be helping your school'. Children are being turned into consumers too young."

Mrs Rutter said teachers also dipped into their own pockets to buy their own books to teach the literacy and numeracy hours.

In his speech, the ATL's president, Eddie Ferguson, said: "In the world's fourth wealthiest nation, we have schools collecting Tesco vouchers in order to buy books and basic equipment. We have teachers organising jumble sales to save their colleagues from redundancy. Is this the way to run education?"

A spokesman for the education department said: "The ATL is talking complete nonsense. We are spending £540 more per pupil in real terms between 1997 and 2001. The greatest proportion of that is spent in primary schools." The government was relaxed about companies offering aid to schools, which were offering "peripheral help".