Thousands of public servants went on strike across the country, joining picket lines and rallies to call for pay increases.

Speaking in Wellington, where hundreds of striking workers gathered outside the Beehive, Public Service Association national secretary Fleur Fitzsimons said 10,000 public servants had taken part in Wednesday's industrial action.

"When 10,000 public servants are saying that public services are underfunded, that they're burnt-out, and that they need a better offer, they deserve us to listen," she said in a video taken from the capital's picket line.

"We've had amazing support from other unions and New Zealanders all over the country.

"We will stay strong until we get a fair deal for these public servants, their families, and the public services that all New Zealanders rely on," she said.

PSA members were on strike in Christchurch on Wednesday. Photo: RNZ/Nathan McKinnon

Earlier on Wednesday, PSA national secretary Duane Leo told RNZ the strike action was a "last resort" to get a better pay offer in ongoing negotiations, given the consumer price index was at 4.1 percent.

"We've been offered considerably less than that. Members will not take a pay cut in this round of bargaining in the environment that we're in at the moment," he said.

Multiple politicians joined the striking workers on Wednesday, including Labour leader Chris Hipkins and Greens co-leaders Chlöe Swarbrick and Marama Davidson.

Hundreds gathered in the capital for Wednesday's strike. Photo: RNZ / Zachary Cornelisen

Hipkins said he stood in solidarity with striking workers.

"You deserve better, but New Zealanders deserve better… we won't cut our way to a better public service.

"Your rights at work matter, you should be able to go to work every day and come home safely.

"This is a government that doesn't respect the work you do every day."

On the picket lines, workers and union delegates said they were struggling with the rising cost of living.

One DIA worker in Auckland said she was "sick of praises, we just need a raise".

"Everything is going up, but we're still getting the same. How does that work?" she said.

Workers and union delegates said the cost of living had taken a toll. Photo: RNZ / Zachary Cornelisen

In Christchurch, PSA organiser John Stace said he wanted the government "to invest in our people".

"Austerity does not work," he told RNZ.

"It's tough. These members do their job because they have a passion for doing it and part of that passion for the job means they're interacting every day with people who are under pressure themselves," he said.

Assistant secretary Jayne Macfarlane echoed other PSA members' concerns.

"They are ordinary people, dedicated to getting outcomes for New Zealanders. In some places it's becoming more difficult due to economic downturn and the call on public services to support these people every day," she said.

Last week, Prime Minister Christopher Luxon said public servants should be at work or they should be around the table negotiating.