Construction unions are to carry out a "protective" ballot for industrial action, up to and including strike action, in case any employers attempt to reduce pay and conditions following last week's High Court ruling that legislation underpinning sectoral wage-setting mechanisms was unconstitutional.

The Industrial Relations (Amendment) Act 2015 was intended to remedy constitutional flaws in previous legislation, which allowed for legally enforceable sectoral wage agreements governing pay and conditions of employment.

However, Mr Justice Garrett Simons ruled that the 2015 act was also flawed and deemed the provisions governing the wage-setting mechanisms unconstitutional.

The judge was also highly critical of the Labour Court and the Minister for Business Enterprise and Innovation in how they had purported to make and confirm a Sectoral Employment Order for the electrical contracting sector.

In today's statement, the Construction Industry Committee of the Irish Congress of Trade Unions (ICTU) said the High Court decision would have implications for thousands of workers in the construction sector.

The five unions involved - SIPTU, Connect, BATU, OPATSI and Unite - said they had decided to carry out a protective ballot of all their members in the sector "... seeking a mandate for industrial action up to and including strike action, should any employer move to unilaterally reduce the terms and conditions of employment of any worker".

The ballot will be conducted over the coming weeks, and in the interim, the Congress Committee will also seek an urgent meeting with the Construction Industry Federation.

ICTU's General Secretary, Patricia King, said she hopes the Government will make a decision very soon to appeal last week's High Court ruling, which could potentially affect tens of thousands of construction workers.

Speaking on RTÉ’s Drivetime, Ms King said she hope the Tánaiste and Minister for Enterprise, Trade and Employment Leo Varadkar will initiate or respond to a request to have a dialogue on the matter.

However, ICTU must "defend the terms and conditions of the employees concerned in the construction sector" in the meantime.

She said the five unions involved are seeking the ballot to ensure that if a "rogue employer" decides to "break loose" and not honour the terms and conditions as they have been operating for the last number of years, then "we would have no choice".

This is the "only instrument" that workers have to defend their terms and conditions of employment, Ms King said, because the fixed-wage mechanism has been "declared invalid".

She said "no worker wants to revert to it, no worker wants to get involved in it, but they don't want their income or wages cut".

She said the ruling means it is "open season" for new workers coming into the construction industry, because there is no sectoral employment order that applies to them.

It is a "very bad situation" for them to be in, she said.