By Angela Harrison
BBC News, NASUWT conference, Birmingham
Teachers warn that academies are a threat to their pay and conditions
Teachers have voted to mount a campaign against the government's flagship academy programme.
Delegates from the NASUWT union voted to condemn the government's programme to expand the number of these schools.
The union claims some councils are using school reorganisations as a "Trojan horse" to bring in academies.
The union's annual conference agreed staff in schools set to become academies should ballot for industrial action if they opposed the change.
The teachers' union opposes academies' independence from pay and conditions agreed for teachers at a national level.
They say switching a school to Academy status puts public assets into private ownership, reduces local accountability, allows private sponsors to dictate areas of the curriculum and threatens union representation.
Ian Carr, from Sandwell, said: "This juggernaut is gathering speed and unless we make a stand and campaign against academies, the things the NASUWT holds dear will be swept away like yesterday's newspapers".
From the floor, delegates reported cases where teachers being employed by some academies were being told to "forget about union membership".
Bill Howard said Staffordshire was being "blackmailed" into bringing in an academy.
The Schools Commissioner had offered a "blank cheque" to open an academy there using BSF (Building Schools for the Future) funding, he said. "Staffordshire can't afford to pass up the opportunity to rebuild its schools despite the blackmail," he told the conference.
But the union's leaders believe some local authorities are pleased to hand over responsibility for failing schools to academies and their sponsors, so that the existing school's poor results would no longer blight their league tables.
NASUWT general secretary Chris Keates said: "Claims in some authorities that they are reluctant hosts to academies and trusts are proving false.
"Some local authorities are using school reorganisation plans as a Trojan horse to introduce academies and trusts in order to ditch their responsibilities for schools in their area in need of support."
Hank Roberts, from Brent in London, said: "Does anyone here not believe that the government doesn't intend to privatise all the state schools?
"If they succeed, pay and conditions will worsen and education will suffer. We have to use every weapon in our arsenal including direct action."
The union also voted to affiliate to the campaign group the Anti-Academies Alliance.