LONDON (Reuters) -Britain's BAE Systems and U.S. arms giant Lockheed Martin announced a tie-up between their secretive research units to develop a new uncrewed autonomous air system, a rare research partnership in the red-hot drone sector. 

The pair laid out plans for a "strategic collaboration" between BAE Systems' Falcon Works and Lockheed's Skunk Works at the DSEI arms fair in London on Monday. 

Dave Holmes, managing director of BAE FalconWorks said that by working together, the two could more efficiently and quickly develop a range of systems. 

"Normally, prime organisations would seek to go and develop these things in isolation," Holmes told Reuters. 

"The driver is about delivering a technical solution as soon as possible at an affordable price," he added. 

The world's biggest defence companies, often referred to as "prime" contractors, team up for big platforms such as the F-35 jet, but have rarely collaborated in the fast-growing autonomous arena, where specialist suppliers, such as U.S.-based Anduril, have made inroads in defence.

Their research units, which regularly deal with classified programmes, also rarely disclose their projects or partnerships.

Holmes said the "modular" products to be explored by the two research labs would first aim to counter electronic warfare by putting up "a wall of electronic resistance", allowing aircraft and weapons systems to beat enemy efforts to jam them. 

Both BAE and Lockheed are involved in separate projects to build new generation fighter jets which are likely to include uncrewed assets, which work in tandem with crewed planes.

Holmes would not say when he expected any product to come to market but added that by working jointly, the two companies bring "complementary access to markets". 

Lockheed's Skunk Works has spawned legendary U.S. military aircraft including the U-2 spy plane and the "Blackbird" or SR-71 that could fly from New York to Los Angeles in just over an hour.

The rare tie-up with foreign researchers comes weeks after Lockheed posted $1.6 billion of programme losses, linked partly to a new $950 million charge for a classified Aeronautics program, indicating a setback for Skunk Works.

Lockheed also recently lost a major contest to develop a next-generation fighter to rival Boeing.

"Skunk Works is in need of a visible success after losing the NGAD (next-generation air dominance) contract to Boeing," said aviation historian and journalist Chris Pocock.

"The U-2 also provided a stream of revenue directly to Skunk Works but may soon be retired," said Pocock, author of "Dragon Lady Today," a history of the plane that first flew in 1955.

"Major manufacturers are also facing serious competition in drones from startups with lower costs," he added.

The announcement came at Britain's biggest defence expo where delegates faced about 200 demonstrators outside the exhibition hall holding signs against UK arms exports to Israel.