CANBERRA, Australia - An Australian senator who is British by descent has become the ninth lawmaker to leave Parliament over a 116-year-old constitutional ban on dual nationals running for office that threatens to bring down the government.

Skye Kakoschke-Moore is a member of the Nick Xenophon Team minor party. She said Wednesday she discovered she was British while gathering evidence ahead of a December deadline for Australia-born senators to provide documented proof that they had not inherited the citizenship of an immigrant parent or grandparent.

She will resign when the Senate resumes next week.

The ruling conservative coalition could lose two House of Representative seats in byelections next month over inherited citizenship.

Australia is rare if not unique in the world in banning dual nationals from sitting in Parliament.