A third Turnbull government minister has been caught up in the dual citizenship crisis that has rocked parliament, with Nationals senator Fiona Nash advising she is a British citizen by descent.

Just moments before Parliament rose for a two-week break, the deputy Nationals leader told the Senate that she had received preliminary advice from the British Home Office on Monday that she had received dual-citizenship at birth through her Scottish-born father.

But the government waited to make any announcement until it had received further legal advice from Britain clarifying the situation. That came through on Thursday afternoon.

Prime Minister Malcolm Turnbull convened an urgent cabinet meeting just after 6pm where it was decided, based on advice from the Solicitor-General, that Senator Nash did not have to resign from either the Senate, or lose her cabinet spot as minister for regional development, regional communications and local government.