The 2006 treaty relates to a temporary maritime border in the Timor Sea and access to oil and gas deposits worth an estimated AU$40 billion (K93.1 billion).
The agreement had outlined a 50-year freeze on negotiations for a permanent border.
But East Timor, also known as Timor-Leste, had claimed the treaty was invalid given Australian intelligence operations in 2004.
History of treaties on Timor Sea:
In 1989 Australia and Indonesia signed the Timor Gap Treaty when East Timor was under Indonesian.
East Timor was left with no permanent maritime border and Indonesia and Australia got to share the wealth in what was known as the Timor Gap.
In 2002 East Timor gained independence and the Timor Sea Treaty was signed, but no permanent maritime border negotiated.
East Timor has long argued the border should sit halfway between it and Australia, placing most of the oil and gas field in their territory.
In 2004 East Timor started negotiating with Australia again about the border. In 2006 the CMATS treaty was signed.
– ABC News