Delegates at both the NUT and NASUWT annual conferences said they would consider balloting members over national action for the first time as the Government presses ahead with its reforms.

So far there have been only local strikes over individual academy proposals.

Since the Coalition came to power last May, the number of academies has increased rapidly, with more than 600 now open and more expected to go live in September.

Academies and free schools are able to set their own pay scales.

Chris Keates, NASUWT general secretary, said that some new academies wanted to follow the national framework, but that a ballot could be necessary if the Government “continues to interfere”.

NUT general secretary Christine Blower said the Government’s agenda was to “drive down teachers’ pay and erode conditions”.

The concerns over pay came as the Government released figures showing that around 700 heads are earning more than pound;100,000 a year. Ms Keates warned that as schools are given more freedoms over pay, higher salaries for management positions will become commonplace and called for all headteachers’ salaries to be published.

Teachers also raised concerns about the growth of free schools leading to children being taught by unqualified teachers.

NUT member Sara Tomlinson said that free schools being set up by journalist and author Toby Young and Katharine Birbalsingh - the former deputy headteacher who lost her job after speaking out at the Conservative party conference - were nothing more than “vanity projects”.

CONFERENCES IN BRIEF

`No confidence’

A vote of “no confidence” in the Government’s education reforms was passed by the NASUWT conference. Teachers called for a campaign against ministers “bulldozing” through changes, including the introduction of free schools and the expansion of academies.

`Insidious’ bigotry

Schools are failing to challenge discrimination against teachers and pupils, the NUT conference heard. Delegates heard that homophobia was “insidious”, particularly in faith schools. Deborah Gwynn from St Helens said a local survey showed that 40 per cent of teachers heard pupils calling other children homophobic names daily.

`Harassing’ the sick

Ill teachers are being “harassed” to return to school while they are on sick leave, according to the NASUWT conference. Teachers in many schools are being asked to set work for their classes while they are absent and expected to come into school for meetings, it was claimed.

Internet warning

Teachers have been warned of the dangers of posting photos of themselves on social networking sites. NUT delegates were told that heads and governors were increasingly searching the internet to screen candidates for jobs.

Parents in the frame

Lack of support from parents is a leading cause of bad behaviour in the classroom, according to a poll of 8,000 teachers. More than two-thirds of respondents said parents were abandoning responsibility for their children at the school gates, with pupils turning up without their homework or even a pen.