SPRINGFIELD - The state's largest employee union filed a lawsuit in federal court Friday in its fight against Gov. Pat Quinn's decision to cancel a series of pay raises for 30,000 government workers.

The American Federation of State, County and Municipal Employees union said the Democratic governor could have used other options to resolve a dispute with lawmakers over the state budget that Quinn says left him with no other choice than to rescind the wage increases outlined in a contract he renegotiated last year.

The suit, filed in the federal court's Central District of Illinois in Springfield, suggests a handful of options Quinn could have used to deal with the state's budget woes.

"The State could slow its procedures for filling positions that become vacant during the 2012 fiscal year or impose a freeze on filling positions as they become vacant in the departments subject to the pay freeze," the suit notes.

Quinn announced July 1 he would rescind pay increases for an estimated 30,000 unionized state workers in 14 agencies, including prison guards and public health workers. He said the budget given to him by the General Assembly didn't contain enough money for the raises.

The contract, which he has renegotiated with the union twice during the state's battle against a tide of red ink, calls for a 2 percent bump on July 1, followed by a 1.25 percent wage hike on Jan. 1 and another 2 percent increase on Feb. 1.

The federal suit marks the third potential battleground between the union and the governor over his decision.

AFSCME is seeking a ruling from an independent mediator on whether the raises can be canceled. And a legislative panel could discuss the governor's move at a meeting in Chicago Tuesday.

In its request to the federal court Friday, AFSCME argues Quinn's action to cancel scheduled pay increases is a violation of provisions against the impairment of contracts found in the U.S. and Illinois constitutions, that the pay freeze constitutes a denial of the equal protection of laws under the federal and state constitutions and that by violating the union's collective bargaining agreement, it amounts to breach of contract under the Illinois Public Labor Relations Act.

"AFSCME members do the real work of state government, such as caring for the disabled, preventing child abuse, guarding state prisons and much more," AFSCME Council 31 Executive Director Henry Bayer said. "These hard-working men and women deserve to know that their employer, the governor, will keep his word and honor his commitments under the law."

Quinn spokesman Grant Klinzman responded to the lawsuit with the same statement he issued Thursday. "The administration will take the necessary steps to manage the fiscal year 2012 budget," he said in an email.

On Tuesday, state workers affected by the pay raise issue are scheduled to participate in informational pickets at the prisons, state developmental centers and other facilities where they work.

In a statement to AFSCME members, Bayer said, "We've seen the attacks on collective bargaining rights around the country, and we don't want to let that happen in Illinois. If the Governor can get away with blatantly violating the union contract, you can be sure that other employers will follow suit."