More than 6000 health service workers across New Zealand are striking today, protesting a pay freeze.

The strikes, affecting all public hospitals from 11am to 3pm, involved marches by Service and Food Workers Union (SFWU) members on Queen Street, Auckland, and Parliament.

Orderlies, food service workers, cleaners and security staff country-wide were joined by Public Service Association (PSA) members in the South Island.

Disability support workers across the country were also striking, between 11.30am and 8.30pm.

The rallies and strikes by the 6000 workers were sparked, not only by the wage freeze in district health boards (DHBs), but the expectation low income people were expected to bear the brunt of the economic recession, SFWU national secretary John Ryall said.

"It's not fair. At a time when costs that affect low paid workers are rising out of all proportion - things like rent, electricity, transport costs - that's where all our members' money goes."

In the South Island, more than 800 administration and clerical staff from six DHBs were protesting for pay parity with their North Island counterparts.

The PSA members were on their third strike in seven days over the "pay discrimination", PSA assistant national secretary Warwick Jones said.

The South Island staff clerical staff were paid about $3000 less than their counterparts in the North island, he said.

A release from a spokeswoman for the affected DHBs, issued in lieu of speaking to journalists, stated the hospitals had put contingency plans in place to minimise disruption from the strikes.

About 1160 SFWU members from 17 DHBs were striking, spokeswoman Karen Roach said.

"We value our staff who are doing valuable work in the DHBs. Maintaining good relations with them is a priority for us, but the reality is we are facing tough financial restraints.

"Wage growth in the health sector has outstripped both inflation and wage growth across the rest of the economy in the past decade," she said.