Tasmanian Senator Jacqui Lambie has stood down from parliament after the UK Home Office confirmed she is a dual-citizen because of her Scottish father.

"It is with great regret that I have to inform you that I had been found ineligible by way of dual citizenship," she told her Senate colleagues this afternoon.

Earlier this morning, Ms. Lambie explained to a Launceston radio station was convinced that she was Australian and only Australian after reassurances from her father.  But the resignation of Stephen Parry made her realize it was time to double check.

"When Stephen Parry came out and mentioned a boat and a date, I'm obviously doing my autobiography, I've gone back over Dad's stuff and straight away I just thought 'oh my God'," she said.  "My whole gut just dropped and I thought 'I'm in trouble here', so I'm on the phone to dad going 'please, what's going on', and it obviously unraveled within about two or three days," she continued.  "By Thursday last week I rang him and I said, 'Dad, I'm gone, aren't I?' and he said 'you know what sweetheart? I think we're gone'."

"I don't know who feels worse - me or my dad.  I think we're both gutted," Lambie lamented.  "We're not sharing love for the bagpipes this morning I can tell you."

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She says she will not stand in the Tasmanian election, but will not rule out a return to Federal politics sometime in the future.

Five other Senators have fallen afoul of Section 44 of the Australian Constitution:  Scott Ludlam and Larissa Waters of the Greens; the Nationals' deputy leader Fiona Nash; One Nation's Malcolm Roberts; and Senate president Stephen Parry of the Liberals.

In addition, Liberal MP John Alexander of the lower house resigned over the weekend, triggering a by-election in Bennelong in which he will face off against former NSW Premier Kristina Keneally for Labor.  Former Deputy PM Barnaby Joyce is contesting his seat of New England after being ruled ineligible by the High Court.