The President of the Irish Congress of Trade Unions Kevin Callinan has warned that the current public sector pay talks will fail if living standards deficits in 2021 and 2022 are not adequately addressed.

In an update to members of ICTU's Public Services Committee, Mr Callinan said unions have agreed to discuss an extension of the current public sector pay deal 'Building Momentum' into 2023.

But he said this will not be a substitute for the cost-of-living impacts felt by members this year and last year.

"We are working in good faith to avoid such an outcome, which would fundamentally destabilise Building Momentum and make impossible an extension of the agreement into 2023," Mr Callinan said.

Formal public sector pay talks between the Government and unions began yesterday at the Workplace Relations Commission and are continuing today.

It comes after unions triggered a review clause within the existing public sector pay deal due to rising inflation.

Under the current agreement, public sector workers received a 1% pay increase last year, with a further 1% due in October.

Unions have not yet said what percentage pay increase they are seeking.

But they have said their focus will be on the gap that has emerged between where inflation is now and where it was when the original public sector pay deal was agreed.

"In 2021, the gap between annualised Building Momentum increases and annualised inflation was 2.15%. If inflation averages 7% this year, and it could be higher, the 2022 gap would be 6.75%," ICTU President Kevin Callinan said in his update today.

"Despite some media speculation, the WRC-brokered public service talks are not discussing wider cost-of-living measures or tax and benefit changes," he added.

Mr Callinan also said that the Government's preference to reach an agreement in advance of October's Budget means that the timetable for negotiations and ballots is challenging.

Minister for Public Expenditure and Reform Michael McGrath said last week that the Government believes there is a basis to proceed and enter formal pay negotiations.

However, he said that success is not guaranteed and that the negotiations will be difficult against a challenging backdrop of global economic uncertainty and rising inflation.

Both sides have said they expect the talks to be intense and that they could conclude, with or without a deal, within a week or two.