The Association of Secondary Teachers Ireland - which represents two-thirds of teachers in church-linked secondaries - has set a deadline of a week for a broad formula to emerge that could allow the pay rise.

The action had threatened to disrupt the national junior and senior leaving certificate exams for 15 and 17-year-olds.

The union relented after Taoiseach Bertie Ahern offered to repay “without prejudice” three days’ pay that was docked last month when staff engaged in a work-to-rule, but only if they came bac to the negotiations.

But agreeing to its demand will not be easy as it would breach the terms of the national “social partnership” pay agreement struck by unions in the public sector. Other unions would not accept a “sweetheart” deal for teachers. Moreover, the two other teacher unions are staying within the national agreement.

Mr Ahern has infuriated the ASTI by accusing some members of a “crusade” against social partnership and possibly against the government.

The executive of the union meets tomorrow and is expected to set a further deadline of three to four weeks for a definite cash offer - otherwise strikes may resume.