With over 200 Australian in Syria, several of them for aid work and some others fighting for the jihadist cause, former Foreign Minister Bob Carr has said the government should look at options to ban the return of Australian youth, participating in the fighting.

Mr Carr, who recently resigned his Senate seat and quit politics for a life in academics, urged the federal government to consider ways to ban Australians; who have gone to Syria to participate in the fighting, from returning home.

The former foreign minister said he had lobbied for implementing a punishment for Australians travelling to Syria to participants in the civil conflict. He, however, admitted to having received opinion that there was no way to legal stop Australian citizens from returning.

"I did receive advice that if they are Australian citizens legally you can't stop them returning," he told Sky News on Sunday.

He, therefore, urged the federal government to find ways and options in which they could get around the legal framework to ban the entry of Australian youth, who are participating in the Syrian civil war.

Accepting the difficulty in implementing a provision on this kind, Mr Carr emphasises the need for all political parties to agree on the matter.

"It should be a bipartisan initiative," he said.

Outgoing Senator Carr said, he hoped that the threat of expulsion could help in deterring a lot of "misguided excitable youth from responding to the jihadist cause". There are about 200 Australians who had gone to Syria, he said. But this number included people involved in aid work, he agreed.

"Probably a lot lower number are actually involved in fighting," Senator Carr pointed out.