Michael Gove is heading for a showdown with teaching unions after they announced a fresh round of strikes over pay, pensions and conditions.
The National Union of Teachers (NUT) and the NASUWT accused the Education Secretary of being "reckless and irresponsible" as they said members in eight English regions will stage walkouts on two days next month.
Mr Gove hit back, declaring there was "no excuse" for strikes, and accusing the union leaders of attacking teaching.
Hundreds of thousands of pupils in thousands of primary and secondary schools are likely to be affected by the new wave of industrial action.
NUT and NASUWT members in the East Midlands, West Midlands, Yorkshire and Humberside and the Eastern region will take part in a walkout on October 1, the unions announced. Those in the North East, London, the South East and the South West will strike on October 17. A national one-day walkout is expected to follow before Christmas.
NASUWT general secretary Chris Keates said the latest move was not a "reckless rush" to strike action, and that they had been trying to engage with Mr Gove since he came to office in 2010.
"No one wants to be disrupting children's education," she said. "Our experience is parents understand that if you attack teachers' pay and conditions you are putting at risk children's education."
The unions accused Mr Gove of "megaphone diplomacy", using public platforms to denounce them rather than engaging to discuss the issues.
"Since June Mr Gove has taken to going from one public platform to another using megaphone diplomacy rather than sitting down and engaging frankly", Ms Keates said. "It is a reckless and irresponsible way for a Secretary of State to behave."
At an event in central London on Thursday morning Mr Gove questioned why the unions were pursuing strikes. "There is no excuse for going on strike," he said. "What is the complaint that teachers have? Is it that pensions are poor? It has been pointed out that even after recent changes, teachers have better pensions than the majority in the public and private sectors."