The union says the executive broke a pledge to cut class sizes

The Edinburgh branch of the EIS hopes to win backing for the move at the union's annual general meeting, to be held in Perth in June.

It believes the previous Scottish Executive reneged on a promise to cut class sizes to 20 in key subject areas.

The executive denied this and said it remained committed to achieving the target, albeit with more flexibility.

A commitment on class sizes formed part of Labour's coalition deal with the Liberal Democrats after the 2003 Holyrood election.

Compromise standards

The aim was to cut S1 and S2 maths and English class sizes to a maximum of 20 in a drive to improve numeracy and literacy.

However, in February this year, it emerged that class sizes of up to 29 would be allowed if the overall average could be kept to 20.

The executive claimed the move would give teachers more flexibility but the EIS said this would compromise standards.