Jakarta – Indonesia and Australia, whose relations have been rocky at times, take a step forward tomorrow when they sign a treaty delineating for the first time the maritime boundaries between the two countries.

Indonesian Foreign Minister Ali Alatas and Australian counterpart Alexander Downer will sign the treaty in the West Australian city of Perth, following a series of negotiations on sea boundaries dating back to the late 1960s.

It is also the first major bilateral international treaty to be signed by Australia's Liberal-National coalition government since it came to power in March last year.

Australia and Indonesia have tended to have a love-hate relationship over the years, with Jakarta angered by critical reporting of its policies, particularly over human rights and East Timor.

But this past year various government ministers from Australia have visited Indonesia, and Canberra has made it plain it is taking a pragmatic approach towards trade and investment with its giant northern neighbour of some 200 million people.

Mr Downer said in a statement last September that the maritime agreement "effectively finalises the maritime boundaries between Australia and Indonesia".

"It provides a firm and legal basis in international law for the exploitation of natural resources, both in the water, and on the seabed and below it, and the protection of the marine environment," a diplomatic source said yesterday.

The agreement does not affect the 1989 Timor Gap Treaty which covers exploitation of oil and gas reserves in the Timor Sea between Timor island and Australia.