Christine Blower, general secretary of the National Union of Teachers, the largest teachers union, said the latest government pension proposals would force teachers to work longer, pay more toward their pension and receive much less in retirement, The Daily Telegraph reported.
"The NUT believes it is essential that the teaching profession stands united on this issue," Blower said.
She said union actions in June and November of last year brought concessions from the government, but they don't go far enough.
"We have no evidence whatsoever that teachers' pensions are unaffordable" to the government, Blower said.
She said NUT would work with other teachers unions to "to look at the ways we can work together to defend the profession and our pensions."