A five-week-old strike at Sikorsky Aircraft is causing "rapidly dwindling" supplies of spare parts for a military helicopter used in Iraq and around the world, a U.S. Navy spokesman said.

The strike by 3,500 Teamsters is forcing the Navy to borrow parts from helicopters undergoing maintenance in order to keep the Seahawk helicopters in operation, Capt. Thomas Van Leunen, spokesman for the Navy's chief acquisition officer, told The Associated Press.

"The on-hand supplies are rapidly dwindling," Van Leunen said late Tuesday. "It has started to have a pretty significant impact on the H-60 fleet."

So far, the strike has not affected the ability to operate the fleet, Van Leunen said.

"We're obviously concerned about the long-term impact if the strike does not settle soon," Van Leunen said. "We're obviously concerned the longer the strike goes on it could eventually have an impact on those deployed H-60s."

It is the first acknowledgment that the Sikorsky strike is having an impact on the military. The Navy has about 300 Seahawks in operation around the world, including Iraq and Afghanistan, Van Leunen said.

Sikorsky has not been made aware of a need by the Navy to borrow parts due to the strike, company spokesman Bud Grebey said Wednesday.

"We are aware that fleet readiness is the Navy's highest priority and we are supporting them accordingly," Grebey said. "We're tracking spares down to the part number and delivering them in accordance with the Navy's needs."

Sikorsky officials have said the company is implementing a contingency plan that includes shifting work to facilities out of Connecticut and arranging for contract employees through third-party suppliers. The company also has said the plan calls for hiring replacement workers if necessary. None have been hired so far.

"We are increasing production capacity every day," Grebey said. "Should this strike continue, our contingency plan will bring our operations back to full production. The Navy has been fully briefed on our plan and is supportive of our efforts."

Teamsters have been on strike since Feb. 20 over proposed increases to employees' health insurance contributions in the company's contract offer.

The union and the company have exchanged proposals through a federal mediator in the past week, but each has been rejected.

Sikorsky is a part of United Technologies Corp., based in Hartford.