Officials from Australia and East Timor are planning to meet this week to try and resolve their differences concerning the development of resources in the Timor Sea. Both sides hope to finalize an agreement by May 20th, according to Australian Foreign Minister Alexander Downer. The agreement affects development of large gas fields in the Timor Sea. "We are still working towards finalizing our agreement on May 20 in East Timor but we will have to wait and see how we get on," Downer said. "Things are looking reasonably positive," he said. But "there have been different messages that have come out from different people on different occasions" in East Timor, he added. His comments follow calls in late March for East Timor to seek much more favorable sea bed boundaries between the two countries. Those calls have in part been pushed by Petro Timor, which claims it is the rightful owner of concessions granted in 1974 by Portugal to explore for gas and oil in the Timor Sea. Following Indonesia 's invasion of East Timor in 1975, those claims were replaced by fresh rights awarded to other companies. Following East Timor 's vote in 1999 to separate from Indonesia, Australia and East Timor began negotiating a new treaty that maintains the basic terms of the previous treaty with Indonesia on resources development in the Timor Sea. In July last year, Downer and Australia's then industry minister, Nick Minchin, signed a memorandum of understanding on the issue with the United Nations Transitional Authority in East Timor and East Timor's chief minister, Mari Alkatiri. East Timor has been under U.N. administration since 1999 and is due to gain full independence on May 20. "It is an important priority for us to try to reach an agreement before May 20 because that is when the current Timor Gap treaty expires," Downer said.Downer said the major outstanding issue involves unitization of the Sunrise-Troubador gas field, of which 80% is in Australian territory and 20% is in an Australia-East Timor joint development area. "There are some differences in how that is to be managed," he said. "But we hope those can be resolved as well." "I'm not too pessimistic about that," he said. But "you can't really tell in negotiations," he added.