First flown on 22 December 1974, and built as an engine test bed under official contract, the Mirage F1.M53 was also envisaged as the basis for a contender in the contest to find a successor for the Lockheed F-104G in service with Belgium, Denmark, the Netherlands and Norway. Evolved from the basic Atar 9K-50 turbojet-powered Mirage F1C, the Mirage F1.M53 - referred to for a brief period as the "F1E", the suffix letter signifying Exportation and the designation subsequently being reassigned - was powered by the SNECMA M53 turbofan rated at 5550kg dry and 8500kg with maximum afterburning. M53 installation involved significant fuselage structural redesign, and to provide suitability for ground attack and long-range interdiction tasks in addition to that of interception, provision was made for multi-role avionics. By comparison with the F1C, the F1.M53 had increased fuel capacity, enlarged engine air intakes and strengthened undercarriage. The nose profile was revised to provide for the introduction of a rectractable flight refuelling probe. The installed armament remained two 30mm cannon and it was proposed to distribute up to 4000kg of ordnance between seven external stations. The other contenders for the multi-national fighter contract were the Saab 37 Viggen and the General Dynamics F-16. With choice of the latter as winner of the competition, plans to produce a second prototype F1.M53 for testing and integration of systems were discarded.