One Nation Senator Malcolm Roberts has admitted he did not receive confirmation that he had renounced his British citizenship until December 2016, six months after he nominated to run for the Senate.

In an appearance on Sky News on Thursday night, Senator Roberts claimed he sent a series of emails to the British consulate to check his citizenship status before nominating as a candidate.

He said he sent the first email on May 1, 2016, and sent further emails renouncing his citizenship “effectively immediately” in June, days before signing his nomination form.

“I did it to three different people and that took a month and I didn’t get a response,” he said.

“So now the nomination time is drawing close, so then I said, ‘OK’. I write again, again and again to the British and said, ‘I believe I am not a British citizen, and just in case though, if I am, I renounce it, effective immediately’.”

It was not until December 5 and after a “lot of badgering”, that he received a response confirming the renunciation of his British citizenship, Senator Roberts said. Nominations for the 2016 election closed on June 9.

Matt Canavan has vowed to take his citizenship case to the High Court. Photo: AAP

The TV appearance came as Senator Roberts faced mounting pressure to prove he is eligible under Section 44 of the Constitution – the same rule that saw the resignations of Greens senators Larissa Waters and Scott Ludlam and is now forcing Senator Matt Canavan to fight for his career in the High Court.

During the interview, Sky News host Paul Murray claimed he had seen emails that corroborated the senator’s version of events. A spokesman for Senator Roberts declined to show the documents to The New Daily, saying they have been shown to and “verified by” another news organisation.

Asked if Senator Roberts had called the consulate after his initial emails went unanswered, the spokesman responded: “This matter is now resolved. Thank you for your interest.”

Senator Roberts said he was “very confident” he would win any challenge against his eligibility, adding that he was “very pleased” with legal advice he had received on the matter.

“So I’ve taken all steps that I reasonably believe necessary,” he said.

In a 1992 case involving former MP Phil Cleary, the High Court ruled that a candidate would remain eligible if they took “all reasonable steps” to renounce their previous allegiance.

Any challenge to Senator Roberts’ eligibility would likely hinge on this question.

A citizen must undertake a formal set of steps in order to formally renounce their British citizenship, according to the UK government.

They must fill out a specific form, which must be sent along with supporting documents proving citizenship and a fee.

Earlier in the week, The Australian reported that British High Commission records showed Senator Roberts was born a British citizen, while Buzzfeed revealed that he had travelled on a British passport as a child.

That prompted Senator Roberts to reveal he had renounced his British citizenship, contradicting earlier claims last year that he’d never held citizenship of another nation.

Responding to the inconsistency, a spokesman for Senator Roberts told Fairfax Media: [Malcolm Roberts] is choosing to believe that he was never British. He is preferring to believe that he was never British because he has no allegiance or exercised any citizenship arrangement.”

Senator Roberts was born in India in 1955 to a Welsh father and an Australian mother.

Also on Thursday, the Greens joined Senator Roberts and One Nation in calling for a parliamentary audit of all MPs’ eligibility.