The head of the Workplace Relations Commission, Kiernan Mulvey, has warned that the Landsdowne Road public pay agreement is a "ticking time bomb".

Mr Mulvey claims workers who did not agree to the deal will miss out on the payment of increments which are due to be restored from September.

Primary teachers are the latest group to announce industrial action over increased workload and promotion bans.

Their union the INTO says it will issue a directive on non-cooperation to all primary schools for admin work in the coming days.

Mr Mulvey said there is certain unrest ahead.

The WRC chief said: "We are on a slow ticking time bomb to that situation come September, if people do not adhere to the main tenets of the Landsdowne Road Agreement.

"Then there's implications around, and probably to some degree the first group facing that is probably the teachers about the non-payment of increments and the non-payment of substitution and supervision allowance."