HONOLULU -- There were several major developments Tuesday in the battle between Gov. Linda Lingle and public workers unions.

Unions representing teachers and blue-collar workers asked the courts to block furloughs and the governor said she has already begun planning layoffs if the plans for the three-day-a-month furloughs are blocked.

The moves set the stage for a high-stakes bargaining sessions that begin this week.

"All of our directors are working on layoff plans. We've asked them not to delay that because we know that we could be challenged any day on the furloughs," Lingle said.

Within minutes of the governor's statement, the United Public Workers and Hawaii State Teachers Association filed their complaint, saying the furlough was an un-negotiated 14 percent pay cut and that the Lingle's plan illegally reduces guaranteed retirement benefits. The lawsuits ask for injunctions to block the three-day-a-month furlough.

The state's largest public workers union, the Hawaii Government Employees Association, filed its lawsuit Tuesday afternoon.

"The governor has continued to refuse to negotiate with us and is ignoring the collective bargaining process," HGEA Executive Director Randy Perreira said in a written statement.

"If the unions are successful at blocking the furloughs, we will have to go to mass layoffs and some shutdown of programs," Lingle said.

The governor said she will announce details of the furlough plan as early as Wednesday. Employees may be offered furlough banking, or the option of taking unpaid vacation, she said. Workers will not be furloughed at prisons, the youth correctional facility or state mental hospital, Lingle said.

"The federal government has some involvement in all three of these facilities," she said.

All of these moves set the stage for negotiations later this week to which the federal mediator has been invited.

"It's negotiating how we are going to reduce our labor costs," Lingle said.

The contracts expire June 30. The governor said she will not try to lay off any workers until then.