CANBERRA, Australia (AP) — A second Australian senator in less than a week has announced she's quitting Parliament after discovering she's a dual national and had therefore never really been elected.

Larissa Waters, co-deputy leader of the minor Greens party, said Tuesday that she's quitting after six years as a senator after the Canadian High Commission in Canberra told her that she's Canadian.

On Friday, the Greens' other co-deputy, Scott Ludlam, revealed that he was a citizen of New Zealand as well as Australia, which made him ineligible for the Senate job he's held since July 2008.

Australia's constitution states a "citizen of a foreign power" is not eligible to be elected to Parliament.

Greens Leader Richard Di Natale says the party will tighten procedures to prevent ineligible candidates from running in future elections.