Updated

Another senator's right to sit in the Australian Parliament is under a cloud over a constitutional prohibition on dual citizens being lawmakers that has already ousted two senators in two weeks and threatens a third.

Sen. Malcolm Roberts revealed Thursday he only received written confirmation that he was not a British citizen five months after he was elected in July last year as a representative of the anti-immigration, anti-Muslim One Nation party.

If Roberts were a dual citizen when he was elected, High Court precedent suggests he was ineligible to stand. He could be forced repay his salary and be fined for each day he spent as a senator.

Roberts says he would survive any court challenge to his eligibility.