PROVIDENCE — Woonsocket officials warned the city’s two public safety unions yesterday that if they don’t agree to substantive concessions on pay or benefits, they will lay off about 40 of the community’s 101 police officers and 55 to 60 of its 135 firefighters, possibly by the end of the week.

They did so after a Superior Court judge, ruling on a request by both unions, scuttled the 5 percent pay cuts and 15 percent health coverage contributions that the city unilaterally imposed on both unions two weeks ago in an effort to cut current-year spending by more than $1.2 million.

Representatives of both unions said they were talking with the city; the police union said it had scheduled a meeting for today.

Joseph A. Andriole, staff representative for the Rhode Island chapter of the International Association of Fire Fighters, said the firefighters were proposing their own cost reductions, which he would not detail. He said if the city carries out its threat to issue layoff notices, the union would be back in court the next morning to contest them.

And Gary T. Gentile, general counsel to the International Brotherhood of Police Officers, said the police union was sensitive to the layoff threat.

“It’s looming and, as such, we’re obviously trying to work with them,” he said.

The city argues the layoffs are being forced by Governor Carcieri’s plan for a midyear cut in non-school state aid to cities and towns, a move that would mean a $3.6-million loss for Woonsocket.

City and union representatives made their comments after meeting in chambers with Superior Court Judge Mark A. Pfeiffer. Joseph Rodio, the lawyer representing the city, said Pfeiffer ordered the city to repay the wage cuts and health insurance contributions that began two weeks ago.

Rodio said he told the judge that there was “no alternative but to do layoffs.”

In an affidavit filed with the judge, the city’s planning and development director, Joel Mathews, said that without the pay cuts and health coverage contributions — worth about $729,000 from the firefighters and $530,000 from the police — the city would be unable to make its March 1 payroll.

“Without significant expenditure cuts, the city will be financially insolvent by March 1, 2009,” he said in the affidavit.

The 5-and-15 plan has already been imposed on the city’s nonunion and management employees. The two union locals that represent City Hall workers have agreed to five-month deals that call for unpaid furlough days and employee contributions to health insurance that wound up equaling the financial savings target the city was trying to reach.

Besides salary and benefits cutbacks, the city has begun charging for curbside trash collection and put maintenance of the sewerage system in the hands of a private contractor.

Speaking for the firefighters, Andriole was bitterly critical of the city’s layoff threat, saying with a city as densely settled as Woonsocket, and with so many aging buildings, the layoffs would pose a danger to the remaining firefighters and the city residents.

But Rodio said the problem was simple mathematics. The city doesn’t have enough money to pay the current level of salaries and benefits, he said. Either the union must agree to benefits that cost less or there will have to be fewer firefighters, he said.

jhill@projo.com