CANBERRA, Australia: A fourth Australian senator was referred to the High Court on Wednesday to rule on whether he was legally elected due to a constitutional prohibition on dual citizens becoming lawmakers.

Malcolm Roberts said he was confident he had been eligible for election, but had asked his anti-immigration, anti-Muslim party One Nation to refer him to the court “in the interests of honesty and transparency.”

Roberts had been under intense media scrutiny before he revealed last month that he only received written confirmation that he was not a British citizen five months after he was elected in July last year. But he has declined to say whether he had ever been a dual citizen.

“I have always thought that I was British — that I was Australian, always thought I was Australian,” Roberts said, correcting himself during a news conference on Wednesday.

Roberts declined to say when he lodged a document renouncing British citizenship. He described this step as a precaution.

Roberts, who was born in Disergarh in India in 1955 to an Australian mother and Welsh father, follows senior government Sen. Matt Canavan and two minor Greens party senators, Scott Ludlam and Larissa Waters, in being referred to the court for scrutiny.

New Zealand-born Ludlam and Waters, who was born in Canada, resigned last month after discovering they were citizens of their birth countries. But their party has asked the court to confirm that they were ineligible and to clarify rules around dual citizenship.

Roberts and Australia-born Canavan, who said his mother applied for his Italian citizenship without his permission, are staying in the Senate unless the court declares them ineligible.

According to court precedent, Roberts was illegally elected if he was a British national on the July 2 election date.

One Nation party leader Pauline Hanson said she believes Roberts had been eligible to stand, but described his case as “very complex.” She declined to elaborate.

Greens Leader Richard Di Natale said if One Nation had not asked the Senate to refer Roberts to the High Court, the Greens would have.

“His story has changed more times than I’ve changed underpants,” Di Natale told the Senate.

The Senate later rejected Di Natale’s Senate motion that would have required all senators to be independently audited to ensure they were eligible.

Since the last election, a senator has quit because his indirect ownership of a building in which the government leased his office breached the constitution’s eligibility rules because he was deemed to have had a pecuniary interest in the government contract. The High Court fired another senator who had breached the rules twice by being bankrupt and having a criminal record for stealing the keys from a tow truck to prevent his truck from being repossessed three years ago.

Attorney General George Brandis noted that six of the 76 senators elected in the last election had now been referred to the High Court to rule on their eligibility.

“One might be forgiven for thinking that being a senator is one of the most hazardous occupations in Australia at the moment,” Brandis told the Senate.