Normally fierce rivals, Elbit Systems and Israel Aerospace Industries are co-operating on an upgrade package for elderly Lockheed Martin F-16As.

Israel retired its "Netz" fighters earlier this year and is now looking to sell the 40-strong inventory, which would be extensively modernised by the partners.

No details of the enhancements has been revealed, but the Israeli air force previously upgraded of its F-16C/Ds under the "Barak 2020" initiative.

The aircraft gained an avionics and mission system enhancement, as well as structural strengthening.

Modifications will begin only when a customer has signed for the aircraft.

The F-16As have been in Israeli service since 1980, but most recently have been employed as aggressor aircraft for training missions.