Germany is planning to deploy 1200 troops to help France in the fight against Islamic State jihadists in Syria, its army chief says, in what would be the military's biggest deployment abroad.

'From a military point of view, around 1200 soldiers would be necessary to run the planes and ship,' army chief of staff General Volker Wieker told Bild am Sonntag newspaper, adding that the mission would begin 'very quickly once a mandate is obtained', Sky News reported on Sunday.

'The government is seeking a mandate this year,' said Wieker.

Berlin on Thursday offered France Tornado reconnaissance jets, a naval frigate, aerial refuelling and satellite images in the fight against IS.

Between four and six Tornados would be deployed to deliver images of the ground, even in poor weather and during the night, Wieker said.

Asked why Germany had shied away from participating in direct air strikes, Wieker said the coalition already had 'sufficient forces and means' dealing with that aspect of the battle.

Sources: MENA