Greens senator Scott Ludlam has been forced to stand down from Federal Parliament.
The Western Australian representative is a dual citizen of Australia and New Zealand - meaning he is "ineligible to hold elected office."
Ludlam apologised for the mistake in a written statement saying that he was "personally devastated" to have not corrected the oversight earlier.
Here is what he said:
Ludlam was elected in the 2007 federal election representing WA.