The Northern Ireland Secretary has been urged to match a pay deal accepted by teachers in England for colleagues in the region.
On Monday it was confirmed members of the largest teaching union in England accepted a 6.5% pay rise for teachers and voted to end strikes.
With the Stormont Assembly still collapsed, Northern Ireland Secretary Chris Heaton-Harris is facing a call to match the deal for teachers in the region.
The NASUWT said the 6.5% offered to teachers in England comes after a 5% increase last year while teachers and further education lecturers in Northern Ireland have not had a pay increase for three years.
Justin McCamphill, NASUWT national official Northern Ireland, said it is unacceptable that teachers across the UK are being treated differently.
“NASUWT Northern Ireland members are not prepared to stand by while their pay dwindles and their living costs rise,” he said.
“If the Prime Minister believes that 5% last year and 6.5% this year is good enough for teachers in England, it is simply not acceptable that ministers in his government would treat other UK teachers in a worse manner.”
Mr McCamphill warned that his union is prepared to escalate ongoing industrial action in the new term.