Australia has returned the documents in good faith without acknowledgement that Australia had violated Timor-Leste's sovereign rights, Attorney-General George Brandis said in a statement.

Brandis also expressed his disappointment that Dili was still moving ahead with its International Court of Justice challenge against the validity of a 2006 treaty over maritime borders that sets out how the two nations will share and jointly develop natural resources within the Joint Development Petroleum Area.

Timor-Leste claims that Australia spied on Timorese officials during the treaty negotiations in 2004, and so the CMATS [Certain Maritime Arrangements in the Timor Sea] treaty must be declared void as a consequence.

East Timor has been seeking to have the treaty declared invalid in order to establish a permanent maritime boundary halfway between the two countries, which it hopes would put more of the Greater Sunrise oil and gas field within East Timor's border.

The CMATS treaty gave Timor-Leste 50% of revenues from the $40 billion Greater Sunrise fields despite the fact only a fraction of the Sunrise and Troubadour fields are in Timorese waters.

The nation now wants the boundary set at the equidistant between East Timor and Australia, ignoring Australia's continental shelf, which would substantially increase its revenue.

The Australian government has tried to convince Timor-Leste to return to the negotiating table, and had been granted a six-month hiatus on the arbitration process so the two nations could resolve the matter outside court, but Timorese prime minister Rui Araujo said Australia had refused good faith talks.

Foreign Minister Julie Bishop claims an agreement to develop a plan for talks on a maritime boundary was never part of the deal to put the arbitration on hold.

East Timor is now "reactivating" the underlying arbitration case to have the 2007 Greater Sunrise treaty declared invalid in The Hague.

Greater Sunrise holds an estimated five trillion cubic feet of gas and 225 million barrels of condensate, and was discovered in the 1970s.

Woodside, which operates the Greater Sunrise fields, has said that it will not make any major investments in the project until there is certainty of tenure.

It prefers a floating LNG development, however the Timor Leste government, which derives much of its income from oil and gas developments, wants an onshore LNG plant.