A union leader has warned if the dispute over workers’ pay is not resolved, further industrial action “will be even bigger” and strikes will continue “right through the summer”.

Mark Serwotka, general secretary of The Public and Commercial Services Union – one of the largest unions in the UK – told Sky News ministers should be aware that “the amount of people taking or voting for action is going to grow”.

“It’s not feasible that they can sit back with this unprecedented amount of industrial action growing because it’s half a million today,” he told Kay Burley.

Largest strikes in more than a decade underway – politics latest

“Next week, we have paramedics and we have nurses. There will be the firefighters we know who have now voted for strike action.

“So the amount of people taking or voting for action is going to grow – and I don’t believe the government will find it can get away with putting its head down while all this disruption takes place.

“And I think they’ll be forced to take a much more realistic attitude.

“But if they refuse, we are planning for our campaign to continue right through the summer with both long-term, sustained, targeted strikes – but also mass actions like today.

“And I think we will see if there is another one, it will be even bigger than the one today.”

Tonight at 7pm Sky News will have ‘How to End the Strikes’, a special live programme talking to both sides in today’s industrial action.

Mr Serwotka added there is “a crisis of in-work poverty” – and claimed that 40,000 civil servants are using food banks.

Meanwhile, the leader of the Trades Union Congress (TUC) accused Prime Minister Rishi Sunak and Chancellor Jeremy Hunt of being “missing in action” as hundreds of thousands of workers strike in the biggest day of industrial action for more than a decade.

General secretary of the TUC Paul Nowak told Sky News the government is “playing a little bit fast and loose with the British public” in suggesting that issues around workload, recruitment and retention can be addressed without talking about pay at the same time.

“They’re absolutely connected,” he said.

“And really the government needs to sit down. As I say, the prime minister and the chancellor come to the table, find some new money.”

Read more:
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Mr Nowak added: “I think last time I was on your programme two or three weeks ago, I said that we wanted to sit down with the chancellor and the PM to talk about what could be done in terms of fair pay settlements, new money on the table.

“We haven’t had a response.”

He continued: “I’m an optimist and I’m a negotiator, and I hope that the government will listen and will come to the table.”

Teachers in England and Wales who are members of the National Education Union (NEU) are staging walkouts today – which the union estimates will affect 23,000 schools.

General secretary of the NEU, Mary Bousted, said around 85% of schools across both nations will be fully or partially closed, leaving some parents with no choice but to take leave from work or arrange childcare.

“So unfortunately, about 85% in schools will have been impacted for a strike that didn’t need to happen. if the government had been prepared to negotiate,” she told Sky News.

Education Secretary Gillian Keegan admitted that the government “don’t know” the exact number of schools that have closed their gates but will be publishing that information “this afternoon”.

“We have done a survey which a lot of heads responded to, so that gives us some idea,” she told Kay Burley, adding that “the majority of schools would be open”.

Ms Keegan added that it would be “irresponsible” to offer pay rises in line with inflation.

Train drivers from the RMT and Aslef unions are also staging another strike as a long-running dispute over pay and conditions rumbles on – with university lecturers and bus drivers taking action too.

About 123 government departments are set to be disrupted by industrial action as well.

Protests are being held across the country against the government’s controversial plans for a new law on minimum service levels during strikes.

Speaking from a picket line on Wednesday morning, leader of the Aslef union Mick Whelan told the PA news agency that workers stripped of the right to strike in order to maintain minimum service levels under proposed laws would be reduced to the status of a “slave”.

Downing Street conceded that today’s mass strike action will be “very difficult” for the public.

A Number 10 spokesperson said: “We regret the decision taken by multiple unions to strike as we greatly value the work of their members.

“We want open and honest dialogue about pay.

“Secretaries of state continue to have constructive meetings with their union counterparts, representing a positive step towards increasing dialogue and finding common ground.

“We also want to discuss non-pay concerns including conditions and workload.

“We cannot chase the tail of inflation. Increasing all public sector pay would cost £28bn – equivalent to £1,000 for every household.”

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More strikes are expected next week and will be dominated by NHS staff, with both nurses and ambulance workers planning action.

NHS consultants in England are also preparing for possible strike action.

And the following week will see Border Force officers at four ports strike over four days in the February half-term.