Geneva, Nov 1 (IANS): The Swiss authorities have confirmed that they have arrested three Iraqi citizens who are under suspicion of planning a terrorist attack in Europe.

The office of the attorney general of Switzerland Friday said in a statement that the suspects were arrested and held in pre-trial detention at the end of March, Xinhua reported. The office has been conducting criminal investigations ever since.

It added the arrests were confirmed only now to prevent jeopardising the outcome of ongoing enquiries which "aim to identify possible accomplices and to uncover networks in Switzerland and abroad".

Suspected offences include "supporting the IS (Islamic State) group, misuse of explosives and toxic gases with criminal intent, and encouraging illegal entry to, exit from and residence in Switzerland".

Swiss investigators have called on assistance from European partner authorities and have been working closely with US law enforcement due to the international dimension of the case, it said.

Some 20 legal cases linked to militants are being investigated, including five related to Syria.