General Electric and Rolls-Royce have decided to end self-funded development of an alternative engine for the US Defense Department's F-35 Joint Strike Fighter program, the companies said Friday.

The GE Rolls-Royce Fighter Engine Team (FET) will discontinue development of the F136 engine for the Joint Strike Fighter beyond 2011, they said in a statement.

"The decision, reached jointly by GE and Rolls-Royce leadership, recognizes the continued uncertainty in the development and production schedules for the JSF program," they said.

The companies noted that the Pentagon terminated the engine program in April when its was "almost 80 percent complete," leaving Pratt & Whitney's F135 as the sole engine to power the F-35 stealth jets.

In response, the GE Rolls-Royce team offered to self-fund F136 development through fiscal year 2012, "but will now end its development work.

"The FET will continue to fulfill its termination responsibilities with the federal government," the US-British team said.

"GE and Rolls-Royce are proud of our technology advancements and accomplishments on the F136," said Dan McCormick, president of the FET.

"However, difficult circumstances are converging that impact the potential benefit of a self-funded development effort."

Before the government terminated the program, six F136 development engines had accumulated more than 1,200 hours of testing since early 2009, they said.

The partners said they "consistently delivered on cost and on schedule," and throughout their 15-year program had been leading advocates of defense acquisition reform.

"GE and Rolls-Royce are deeply grateful to our many congressional supporters on both sides of the aisle over these many years as well as the military experts who have supported competing engines for JSF," McCormick said.

"We do not waver in our belief that competition is central to meaningful defense acquisition reform."