A “BIRTHER”-style theory such as the one that dogged Barack Obama’s early presidency has now attached to Prime Minister Tony Abbott.

An online petition with more than 5400 signatories has called on Mr Abbott, who was born in London to a British father, to produce his British citizenship renunciation form.

A spokesman for Mr Abbott last night would say only: “The Prime Minister is an Australian citizen and he does not hold citizenship of any other country.”

His office refused to provide documents verifying this and would not say if Mr Abbott had renounced British citizenship.

The petition claims the PM’s refusal to make the document public raises serious questions about the legality of his election as an MP.

The Constitution requires that MPs not hold citizenship of any “foreign power”.

In the US, “birthers” demanded Mr Obama disclose his birth certificate to show he was born in the US, as required of presidential candidates.

Mr Abbott was born in London in 1957, to a British father and Australian mother, and emigrated in 1960. He got a Rhodes scholarship available only to Australian citizens.