"Disaster, disaster, disaster," should replace the Prime Minister's election slogan of "education, education, education", said the leader of the biggest teachers' union.

In an angry end-of-conference speech, Doug McAvoy told delegates of the National Union of Teachers in Brighton that the union was united behind the campaign against performance-related pay for teachers in England.

Rejecting the promise of "sweeteners" from the government for a more gradual introduction of appraisal-based performance pay, Mr McAvoy told the conference that the ballot for a one-day strike next term would go ahead.

Delivering a broadside attack on the government's education policy, the general secretary mocked "the crazy world of new initiatives" with their "tacky titles and snappy soundbites".

It was a sombre keynote speech for delegates

The greatest rancour was reserved for the government's Green Paper for reforming teachers' pay and conditions, which he said had left teachers "angry and frustrated".

"Let the government understand that we will oppose payment by results. Whatever it might be called, however it might be described, we will recognise it for what it is."

"Disaster will follow," said Mr McAvoy, who accused the government of ignoring common-sense and experience in pursuit of the "brave new world" offered by the Green Paper.

Mr McAvoy called on other teachers' unions to take part in a joint ballot for strike action against the Green Paper, which he predicted would become the "government's self-inflicted agony".

In a warning of battles ahead, Mr McAvoy cautioned members that the government would "scapegoat" and "demonise" the union in its attempts to force through performance-related pay.

Mr McAvoy said the government had to "work with rather than against teachers"

"The government will use all its powers to destabilise our campaign, to frighten our members. It will use all its powers of communication and spin to discredit our campaign."

The largest cheer, in what was a sombre keynote speech, came when Mr McAvoy demanded that "Chris Woodhead should go". Calling for an end to the "custom, culture and practice of Ofsted", Mr McAvoy labelled the embattled chief inspector of schools in England as the "government's own albatross".

While disillusioned with Labour's education agenda, Mr McAvoy stressed there were improvements that needed to be acknowledged. Schools had benefited from extra funding, more pre-school places were available, special needs education had advanced and the curriculum for 16-year-olds was set to be broadened.

But if the government wanted partnership, Mr McAvoy warned, it had to "work with rather than against teachers".

Concluding with a reminder of how seriously he saw the threat from the Green Paper, the general secretary ended the conference with the message that "nothing less than the future of the education service in England and Wales" depended on the outcome of its campaign.