The boss of Italian defence giant Leonardo has slammed the door shut on the possibility of Germany and France joining the Tempest fighter jet programme.

Germany’s own collaboration with France on a sixth generation fighter jet has collapsed, raising speculation that it could join the rival global combat air programme (GCAP), a collaboration between the UK, Italy and Japan.

But Lorenzo Mariani – whose firm Leonardo is part of GCAP - said it would be too disruptive for Germany to join at this stage and the industrial powerhouse would be unlikely to sign up to a junior role in the partnership.

The comments came after Canada signed up as an ‘observer’ to the project.

Mariani said: ‘The only risk is disruption and in the case of Germany I personally think it would be difficult to propose the status of observer.

‘Unless under the status of observer, another nation joining, another group of industries joining the programme would risk producing some delays.

‘At the moment we are all fully committed to the 2035 date for the aircraft.’

Mariani said German industry and the German state ‘were already involved in development in the past few years’.

He added: ‘If I were in their shoes, I would have no reason to start an observer process. Why should I simply observe? I already have matured some experience, I have an industry up and running, industrial capability money, so why should I wait?’

He said France was unlikely to join GCAP ‘for exactly the same reasons’ that its partnership with Germany broke up.

‘The objectives that France has – seen from outside – do not look aligned with the ones of GCAP, especially from the industrial point of view,' he said.