Coalition MP Ann Sudmalis has moved to quash doubts about her citizenship, issuing a statement late on Tuesday that she had been assured by the UK Home Office that she did not hold, and had never held, British citizenship.

As the citizenship crisis engulfing the Federal Parliament deepened, and just a day after Deputy Prime Minister Barnaby Joyce announced he was a dual national of Australia and New Zealand, Ms Sudmalis – the member for Gilmore in NSW – was forced to urgently clarify her status with the British government.

In turn the government turned its sights on Labor on Tuesday, demanding the opposition provide documentation for four of its MPs – Tony Zappia, Maria Vamvakinou, Justine Keay and Susan Lamb.

The government has also suggested Tanya Plibersek, Penny Wong and Anthony Albanese have questions to answer about their citizenship status.