Labor MP David Feeney said he would resign after being unable to prove that he had renounced his UK citizenship.

Last year, nine politicians were ousted over concerns they held dual citizenship - although two later returned through by-elections.

Dual nationals are not allowed to stand for parliament in Australia.

Mr Feeney said he thought he had renounced his British citizenship, but he could not find the paperwork despite "extensive searches".

"I am unable to disprove that I am a dual citizen," Mr Feeney told reporters on Thursday.