The claims, by a head teacher from Leicester, drew an angry response from delegates at the National Association of Head Teachers' conference in Eastbourne.
Frank Gallagher, head of Avenue Junior School, said schools in his area were left with money in the bank at the end of the financial year. On average, a 10-class primary school had enough to pay for four extra teachers, he claimed.
'It is our members who accept the results of gross underfunding. It is our members who acquiesce in rising class sizes. Our members cut down on books while spending money on administrative toys and luxury furniture,' he said.
Mr Gallagher had no apparent support from other delegates, and his remarks were greeted with cries of 'Shame]' and 'Sit down]'
David Hart, general secretary of the association, said afterwards that Mr Gallagher's remarks were 'really quite offensive. This talk about schools having too much money in their budgets is absolute eyewash. Most schools which have kept money back have kept it for a rainy day, and we are facing too many rainy days at present.'
Neil Thornley, a national council member of the association, said parents at his Lancashire secondary school had to come in to do the cleaning because of cash shortages.
'We are having to make people redundant, scratching and scraping to save enough money to redo buildings before they just fall down,' he said.
Colin Moran, head of Henry Moore Middle School in Castle ford, West Yorkshire, said his school had a budget shortfall of pounds 14,000. Without extra money there would be two classes of 10 and 11-year-olds with 83 pupils between them next year, he said.
Norman Fowler, head of St George's Roman Catholic primary school in York, said his desk was at least 100 years old. 'I have a photograph from the turn of the century of my room and that desk is on it. I am not spending money on expensive furniture. There is no reality in what this speaker was saying at all,' he said.
Government tests for 11-year- olds, due to be held nationally for the first time next year, could be wiped out by a teachers' boycott, Mr Hart warned yesterday.
He said that unless the extra workload imposed on teachers was cut significantly, the National Union of Teachers could be rejoined in its boycott of testing by other unions which have ended their action after a promise that the curriculum and testing would be slimmed down.