Headteachers today threatened to bring the government's performance-related pay scheme for schools to a "juddering halt" unless ministers agree to put in £1bn of extra funding.
The National Association of Head Teachers and the Secondary Heads Association are to ballot their members on industrial action involving a boycott which they said would affect teachers - including their own members - but not children.
They said the Department for Education and Skills had failed to provide enough funding to pay bonuses to staff on the upper pay scale, despite ministers' boasts that, with them, good classroom teachers could earn more than £30,000. The two unions have calculated that heads need at least £1bn extra over the next six years to fund the system, which they said was unpopular in schools to start with. The government has provided £250m for the next two years - half what is needed by 2004, said NAHT general secretary David Hart.
About half the 230,000 eligible teachers, deputies and heads would lose out unless the government backed down and found extra money, Mr Hart added.
The headteachers' leaders said they had been driven to taking unprecedented action because ministers had refused to listen to their warnings that paying senior classroom teachers their bonuses this year would mean using money that should be spent on books and equipment for pupils.
The ballots could be held next term at schools across England and Wales and industrial action could begin in time for the Whitsun break.
"We will bring a key part of the government's pay structure, and its belief in performance-related pay, to a juddering halt until it changes its policy. I think we are heading for a confrontation which will bring the government up short and make it understand that heads and their senior colleagues, the school leaders of this country, are saying enough is enough. We are simply fed up with the government expecting us to deliver policies without investing to make them work," said Mr Hart.
Both he and John Dunford, general secretary of SHA, said parents would not understand if heads had to raid budgets for other things, such as books, equipment or recruiting teachers or classroom assistants, to pay bonuses.
But the point of performance-related pay was to reward those who deserved it and if all those teachers who merited it did not get the bonuses they were entitled to, that would damage morale in schools, they warned.
Mr Dunford said former education secretary David Blunkett had raised expectations when he said most teachers who came up to scratch could reach the top of the pay scale with bonuses.
Now teachers were discovering that only a small minority would, in fact, do so, he went on.
The £2,000 bonuses which take teachers on to the upper level of the profession's pay scale would not be affected, as the government has fully funded them separately, said Mr Hart.
If the industrial action went ahead, heads would themselves forgo bonuses worth up to £2,091 depending on the size of the school, he said.
The ballot is the second recent threat of industrial action to emanate from schools. Last week, the National Union of Teachers announced plans to canvass 40,000 members in London over whether to stage a one-day strike in a protest over cost-of-living allowances.
