A judge is barring the city from cutting firefighters’ salaries until they are given the ability to choose from multiple health insurance policies.

State Supreme Court Justice John A. Michalek ordered attorneys for the city and the fire union to return to court June 1.

Mayor Byron W. Brown criticized the decision, even hinting that he believes Michalek has a pro-union bias.

“I’m not surprised by Judge Michalek’s ruling today,” Brown said in written statement. “It was predictable and transparent that he would issue a favorable decision to the union as he has consistently done in the past.”

The city will appeal, Brown added. “We expect that [Michalek] will be reversed at the appellate level, as he has been at least five times since 2008 on labor matters involving the City of

Buffalo,” the mayor said.

Barring a successful appeal, Friday’s twist in a complex dispute will likely stall plans to cut the salaries of about 700 firefighters by 5.5 percent starting with paychecks distributed in mid-May.

“As a result of today’s court ruling, it appears unlikely that the city administration could legally implement the payroll-reduction portion before June 1,” Comptroller Andrew A. SanFilippo said in a written statement. “At this point, it would be pure speculation to identify a specific implementation date.”

Michalek made it clear that the city must return to an earlier policy of offering multiple health insurers before it eliminates a 5.5 percent raise that was given to firefighters in 2007.

Earlier this month, Michalek ruled that the city must comply with a decision rendered last fall by the state’s highest court. The Court of Appeals nullified a 2005 arbitration award that granted raises to firefighters but also made numerous policy changes that infuriated the union.

The high court and Michalek ruled that the city must return to the status quo, restoring various benefits while eliminating the raise. One key issue involves the city expanding its health insurance options beyond the current single provider.

All provisions in effect in 2007 must be restored until a new arbitration panel reviews the issue, including policies governing firefighters who are injured on duty. The fire union initiated the court fight.

The earlier ruling would not only result in firefighters forfeiting the 5.5 percent raise, it would also require the average firefighter to pay back between $11,500 and $12,000 in salary and overtime for payments made over the past 34 months.

Michalek sided with the union’s argument that the city cannot “cherry-pick” which options it plans to restore. “[The judge] specifically said you cannot take away the wages until the health provisions are in place. And that’s the position we’ve had from the beginning,” said Jonathan G. Johnsen, an attorney for the fire union.

The judge also indicated that he had some earlier “concerns about the manner in which the city had conducted its affairs” in this case. Michalek did not elaborate on the concerns in court except to clarify that he was referring to past actions — not efforts that the city is currently making.

Sean P. Beiter, a private attorney representing the city, wouldn’t comment as he left the courtroom. But during the hearing, Beiter said the city is making efforts to comply with all changes required by the appeals court ruling. He said insurance companies have been contacted and other steps have been taken.

“We don’t want to be in violation of the contract,” said Beiter.

The city’s plan to reduce the salaries of an estimated 700 firefighters by mid-May could be placed on hold for months if that’s how long it takes the city to renew agreements with multiple insurance providers.