Canterbury's health system is in a critical condition with medical workers near breaking point.

Information released under the Official Information Act reveals staff are stressed and overworked, services are clogged, and expenditure is at its limit.

The government has put $70 million aside to relieve pressure on staff - but data released under the Official Information Act shows they'll need at least three times that.

The New Zealand Nurses Organisation believes the government needs to urgently up the level of funding to address the crisis.

Spokesperson Lesley Harry claims the worse case scenario is incoming wide spread absences of staff.

"We already have reports of increased sick leave, the workforce is at breaking point and it needs to be addressed. Seventy million in extra funding is just not going to cut it," Harry said.

With specific health care needs in Canterbury, combined with subsidising migrant workers, it's nowhere near enough, she said, also stating the government has lost track of the numbers of migrant workers flocking to the region.

"They need an additional ten-point-five million just to address overseas workforce needs, and they've been allocated two-point-five million a year just to address the overseas workforce."

"It's fairly common knowledge that there are many contributing to the rebuild, and they're not being funded for."