TORONTO -- Premier Kathleen Wynne likes to paint the Progressive Conservatives as the instigators of labour unrest, but she's the one waging war, union leaders said Wednesday.

Six public sector unions representing about 57,000 members are issuing a call to arms and joining forces to fight what they're calling "devastating" cuts to Ontario civil servants.

"We will not let the government pick us off one at a time," said Gary Gannage, president of the Association of Management, Administrative and Professional Crown Employees of Ontario.

The governing Liberals are demanding cuts, clawbacks and concessions on health and retiree benefits, sick pay and salary progression, he said.

It flies in the face of Wynne's recent comments that it would be a mistake to "declare a war on labour" as the Progressive Conservatives would do if they were in power, he said.

"I feel like posting that statement on the door of the negotiating rooms that I'm currently spending most of my days in, because it feels like war has been declared," Gannage said.

It hasn't been this bad in the 34 years he's been in the public service, he said. That's why the six unions have signed a "historic" pact to stick together, he added, something that hasn't been seen since the previous NDP government imposed austerity measures on the civil service -- including the notorious unpaid "Rae Days."

The group includes the Ontario Public Service Employees Union, which represents 35,000 government workers, and the Professional Engineers, Government of Ontario, which represents 615 surveyors and engineers who work directly for the province.

"We've got a lot of experience with burn barrels, strike lines and how to shut down the Ministry of Finance," said OPSEU president Warren (Smokey) Thomas.

He said he doesn't understand why the Liberals are picking a fight with the public service. At least the Tories have been honest that they'd force a pay freeze, Thomas said.

"Even (Tory Leader Tim) Hudak, he'll just pass legislation, he wouldn't torture you so long at the table and cost you a lot of money," he said. "He'd just go screw you."

PEGO, which agreed to a two-year wage freeze in 2013, said its members take their role in protecting the public seriously and don't want to be concerned about potential cuts to their pensions and benefits.

"We want to make sure that the food you eat is going to be safe, the water you drink is going to be safe," said union president Ping Wu.

Government Services Minister John Milloy had little to say in response, insisting he won't negotiate through the media.

"Talks are continuing and I always remain confident and optimistic that we're going to reach a deal that's in everyone's best interest," he said.

Milloy wouldn't say what the government is seeking in its negotiations with AMAPCEO. But the union said the Liberals are effectively demanding a wage freeze for four more years and a halt to merit pay for most employees, which would prevent them from moving within their salary range.

The government is also trying to reduce long-term disability benefits and slash pensionable income for employees with a disability, among other things, the union said.

In 2010, the cash-strapped Liberals announced they would seek to freeze wages for two years from the public sector to balance the books.

Some groups have been able to negotiate hefty pay raises since then, such as this year's 8.5 per cent increase for the Ontario Provincial Police. Wynne also re-opened talks with public school teachers after the government made the controversial move to force contracts on them that froze their wages.

Gannage said he won't slam other unions for successfully negotiating new collective agreements, but there is "inconsistency" in the government's approach.

"In this season, there seems to be some availability to form partnerships with certain groups," he said.

"And then, you know, turn the corner and all of a sudden, the fiscal situation is so terrible that you have find your own offsets to pay for your own increases."

AMAPCEO, which represents 11,500 professional and supervisor employees, said negotiations are currently deadlocked and the two sides are in mediation.

The union received a 94-per-cent vote in favour in its strike vote in late March.