The United States has given the go-ahead for its ally France to buy four Lockheed Martin C-130J military aircraft, a rival to the French-built Airbus A400M.

The US Defense Security Cooperation Agency said the contract for two C-130J transports and two KC-130J fuel tankers would come to $650 million (606 million euros).

Each plane will be fitted with AE-2100D engines from British-based firm Rolls Royce, and France will buy four spare motors along with onboard radar and radios.

“The C-130Js will provide critical transport, air drop, and resupply to thousands of French troops in support of current and future operations,” the US agency said.

“The KC-130Js will provide crucial air refuelling capability to France’s fighter aircraft, light transport aircraft and helicopters,” it added, in a statement.

“France requests that Lockheed Martin be the sole source provider.”

France was a launch customer for the Airbus A400M transport, a direct rival of Lockheed Martin’s C-130J, a stretched version of the tried and tested C-130 series.

But the French military only received the first of its theoretically more modern Airbus turboprops after years of technical problems, cost overruns and accidents.

In May, an A400M crashed in Spain during a test flight, killing four, and several European and Asian customers temporarily halted testing pending an investigation.

Airbus is now delivering the plane again and seeking to build its customer base, but an order from its home country for a US rival could be seen as a bad sign.

Loren Thompson, national security academic and chief operating officer of the Lexington Institute, saw the French sale an “impressive testament” to the C-130.

The plane first went into service with the US military in the 1950s and is now an industry standard in service with air forces around the world in many variants.

Operating costs for the C-130 are low and, Thompson said, “it has the longest in service life of any military aircraft in history” with no end in sight.

“This plane may be in use for a century,” he said. Thompson’s Lexington Institute think tank receives funds from US defense contractors, including Lockheed Martin.