The likelihood of a new wave of public-sector strike action has dominated the start of the annual TUC conference in Brighton.

The National Union of Teachers announced that its members had voted “overwhelmingly” for joint industrial action with NASUWT, in a bid to improve working conditions.

The two unions, which represent nine out of 10 teachers, will be taking action short of a strike on 26 September in English and Welsh schools.

Unison and the GMB also announced that they would be campaigning against government cuts, while the Public and Commercial Services Union (PCS) went further by calling for more co-ordinated strike action, similar to the two national walkouts last year.

PCS general secretary Mark Serwotka said that anti-cut demonstrations organised by the TUC for 20 October should be closely followed by synchronised strike action over changes to public-sector pay and pensions.

“The demonstrations on 20 October will send an important message to government ministers that we do not want their cuts and that there is an alternative,” he said.

“As well as protesting on the streets, we believe we will need to follow this up as soon as possible with further co-ordinated strikes, bringing unions together across the public and private sectors.”

TUC general secretary Brendan Barber, who will be handing over to his successor Frances O’Grady in the autumn, opened the conference by highlighting what he described as the “£7,000 wage grab”.

A new report from the TUC found that since the 1980s, the rise in average employee income had not matched the UK’s economic growth.

Barber explained: “The average full-time worker is now paid around £26,000 a year. But if wages had grown in line with economic growth, and if the gap between those right at the top and the rest had not increased, the average worker would now be getting £33,000 a year – a £7,000 pay rise.”

But a report last week from the Policy Exchange think-tank suggested that regional pay should be brought in for public-sector workers, to make local labour markets fairer. Unions oppose this model, and pay and bargaining rights are set to be one of the central issues for discussion at the TUC congress.

NHS Employers today used the opportunity to urge health service unions to be “creative and brave”, and finally agree a national pay deal.

Dean Royles, director of NHS Employers, said that trade unions were part of the solution to the financial challenges facing the public sector, but that they needed to be flexible if they wanted to preserve national pay bargaining in the NHS.

“The pay bill represents over 65 per cent of [NHS] employers’ cost and, despite a pay freeze, it continues to increase as a result of incremental progression,” he added. “The NHS needs a deal that is more affordable, sustainable and responsive to deliver best value for our patients and better job security for our staff.”