Citizenship proposal a shambles: Marles

Opposition immigration spokesman Richard Marles says the government's handling of plans to strip citizenship from dual nationals involved in terrorism has been a "complete shambles".

Reports of up to six cabinet ministers questioning the proposal have been answered with a petition signed by 40 backbenchers calling for the toughest possible measures against Australian supporters of extremist groups.

Mr Marles told ABC radio on Tuesday he is concerned the proposal could extend to sole nationals and the minister has been unable to explain the legislation, which "may or may not" come before parliament.

Sarah Henderson was one of the Liberal MPs to sign the letter to Tony Abbott but she says safeguards are needed.

"I need to know if there are tougher rules against citizenship, then we can't be in a position where we leave someone stateless," she told ABC TV on Tuesday.