A public sector pay issue sparking the planned largest strike in recent times in Northern Ireland can be resolved now if the Secretary of State acts, trade unions have said.

Teachers, nurses, health workers, education support workers, police staff and civil servants are among those who are to take part in a generalised day of action on January 18 over an outstanding pay award for public sector workers.

The 14 trade unions involved have a combined membership of more than 150,000 workers who are set to take part in large-scale demonstrations and parades across the region.

Economist Esmond Birnie has estimated an economic loss due to the strike of more than £10 million.

However, the Irish Congress of Trade Unions (ICTU) said the issue is simple and “can be resolved now”.

The Stormont Assembly has been effectively collapsed for almost two years following DUP protest action over post-Brexit trading arrangements.

In December, the Stormont parties were told of a £3.3 billion financial package to accompany the return of devolved Government – including money to make an outstanding pay award to public sector workers.

An NIO spokesperson said the Secretary of State and the UK Government “have no authority to negotiate public sector pay”, and said the financial package will remain on the table until a new executive is formed to allocate it.

ICTU assistant general secretary, Gerry Murphy has urged Secretary of State Chris Heaton-Harris to intervene and deliver the pay award.

“The 18th of January will see the largest day of industrial action experienced here in a generation when trade unionists working across our public services strike in support of their reasonable demand for a fair pay rise,” he said.

“A huge range of workers will simultaneously cease work for one day to highlight the fact that the Secretary of State, Chris Heaton-Harris remains unwilling to pay public servants a fair increase or even speak to the trade union leadership. Our offer of talks has gone unacknowledged.”

He went on: “The moral case for fair pay has been conceded by Mr Heaton-Harris when he accepted that these essential public servants deserve an increase. He confirmed he has the money available to make the necessary payments. Yet he’s refusing to release the necessary funds.

“His perverse reasoning appears to be that these salaries are a matter for the NI Executive and the local civil service to sort out with their employees.

“Does he really think that by withholding the funds to pay the increases he can generate sufficient political pressure on MLAs and ministers to force those refusing to return, back into the Executive?

“This is an ill-judged and cynical attempt to manipulate these workers and society more generally. Mr Heaton- Harris is clearly ignorant of the northern Irish character. His dismissive attitude partly explains the enormous levels of public support for these workers who have been left with no option but to strike.

“The issue for our public servants is simple and it can be resolved now. All Mr Heaton-Harris has to do is the decent thing. Make the money available to pay public servants the fair increases that are due.

Meanwhile, on Thursday, the National Education Union (NEU) declared it will join the January 18 strike.

It is now for the NI Parties to come together, restore the executive and begin to address the challenges facing the people of Northern Ireland, including public sector pay

The NEU joint regional secretary, Pauline Buchanan, said: “2024 has brought no change for our members, because of the failure of political talks we cannot accept that pay can be held down even longer. Again, we must take strike action to have our voice heard.

“Teachers have not received a pay rise since September 2020. Since then, the real value of teachers pay against RPI has been cut by 28%.

“The key focus of those who have the authority to offer a pay rise should be on repairing the damage done to teachers pay and living standards. This means a well-deserved and long overdue significant rise – now.”

A Northern Ireland Office spokesperson responded saying: “The Secretary of State and the UK Government have no authority to negotiate public sector pay in Northern Ireland. It is for the relevant NI departments to negotiate pay policies.

“The Secretary of State has expressed his disappointment that a new executive was not up and running to take the offer on the table and deliver it for the people of Northern Ireland before Christmas.

“The fair and generous package offered by the UK Government is worth over £3bn, including money to address public sector pay, and more than £1bn to stabilise Northern Ireland’s public services.

“However, this package is on the table and will remain there, available on day one of an incoming Northern Ireland Executive to take up.

“It is now for the NI Parties to come together, restore the executive and begin to address the challenges facing the people of Northern Ireland, including public sector pay.”