Teachers urged to end co-operation with school inspections
The NASUWT union has told its members to end co-operation with school inspections.
Teachers belonging to the union will not partake in school inspections by the Education and Training Inspectorate (ETI) from 1 February.
Three other teaching unions - the INTO, UTU and ATL - are already taking similar action in a dispute over pay.
NASUWT members in Belfast and Newtownabbey staged a one-day strike in November.
Teachers belonging to the union in Derry City, Strabane, Mid Ulster, Fermanagh and Omagh council areas will hold a further strike on 31 January.
Members of the INTO union also held a half-day strike on 18 January.
The NASUWT has now announced an escalation of action short of strike action, which includes a range of measures.
As well as refusing to co-operate with school inspections, NASUWT members will end participation in CCEA end of key stage assessments.
The union has also instructed them not to attend "any meetings or events" during or after school, "or during the lunch break".
In October, all teaching unions in Northern Ireland rejected an offer that would have seen their pay frozen last year and a rise of 1% for 2016-17.
Education Minister Peter Weir had previously criticised the industrial action.
"I would ask teaching unions to reflect on any planned disruption, as industrial action is not in the interests of children, schools or teachers themselves," he said.
"I would urge them to go back to the negotiating table for future years and to accept that the pay offer they walked away from is not in a position to be improved upon."