the same requirement was the somewhat larger Char Batignolles-Châtillon. A derived medium tank prototype of the latter, made in 1955, proved that it was possible to produce a tank with a first-rate gun and frontally protected with steel equivalence within a weight constraint of . This revived interest in the medium tank concept. In 1956, the WEU defence workgroup FINBEL (named after France, Italy, Netherlands, Belgium and Luxembourg), founded in 1953 and consisting of representatives of the various General Staffs, drafted a set of specifications for a new medium tank to eventually replace their American and British tanks. That same year, Germany joined the workgroup, turning it into FINABEL (the added "A" standing for Allemagne, "Germany" in French) and on 27 October 1956 at Colomb-Béchar a bilateral agreement was concluded between France and Germany to collaborate in building a tank. Though the other FINABEL nations did not formally participate, the type was called Europa-Panzer to indicate its common European nature, and experts from all countries were involved in the design process. The specifications (FINABEL 3A5) for the new tank called for a lightweight and mobile battle tank, setting the weight limit to and compromising the ability to heavily armour the vehicle. French and German engineers, during a conference in Bonn on 12 February 1957, defined the requirements for the future tank. This included a maximum width of , a height of and a tank gun, to be developed by the Franco-German military research institute at Saint Louis. The new tank would have an air-cooled, petrol engine, a torsion bar suspension with hydraulic shocks, a power-to-weight ratio of at least /metric ton and a road range of at least . In May, Italy joined the project, though only nominally, without any material contribution, because after the war it had no tank design bureaus. That same year, on 28 November, the French and German ministries of defence in Paris agreed upon a contract which would allow both countries to produce two prototypes separately. The next year, however, the project suffered a first setback when Charles de Gaulle took power in France, creating the Fifth Republic: the Paris treaty had as its main point developing a common nuclear weapon and on 17 June 1958 de Gaulle decided to refuse Germany and Italy the atomic bomb, to avoid antagonizing the US and United Kingdom. This made Germany lose much interest in a common tank