Tanya Nolan: East Timor and Australia will this afternoon start nearly a week of talks, on the increasingly tense issue of a permanent maritime boundary.

And in the lead-up to the meeting in Dili, East Timor has turned up the pressure by threatening not to ratify an agreement for a seabed oil and gas project, worth $8 billion. From Canberra, Graeme Dobell reports.

Graeme Dobell: The language from East Timor is getting tougher.

Mari Alkatiri: Sometime, even between friends, between good friends, we have a lot of differences, and when there is a lot of money involved it is much easier to have differences between friends.

Graeme Dobell: Prime Minister Mari Alkatiri says he no longer thinks of the Australian Government as a good partner.

Mari Alkatiri: Suddenly, I realise that when billions of dollars are involved, they became really bad partners.

Graeme Dobell: The East Timor leader is getting increasingly sharp in the language he uses to describe a deal his Government signed last year to allow the development of the Greater Sunrise oil and gas field in the Timor Sea.

About 80 per cent of the proceeds from the massive project will go to Australia. The Australian Parliament has ratified the so-called Unitisation Agreement, but Prime Minister Alkatiri now says he won't put the deal to his Parliament to be ratified.

Australia's Foreign Minister, Alexander Downer, says East Timor should carry through and legally ratify what it signed up to.

Alexander Downer: We reached an agreement with them last year, and I flew to Dili and I signed that agreement with the East Timorese Government, one of their ministers signed it, but in the presence of Prime Minister Alkatari and President Xanana Gusmao. And having reached an agreement with them, and signed an agreement, we wouldn't have signed it if we didn't think it was a worthy agreement, and I guess they wouldn't have either.

Graeme Dobell: The hint from Dili, from Mari Alkatiri though, is that any ratification will be linked to progress on negotiations to define a permanent seabed boundary between Australia and East Timor, which he thinks should give much more territory to East Timor.

Mari Alkatiri: I'm still working to get Australia to change its position, because when I had decided to sign the agreements, it was with good faith and I would like to keep this good faith alive, and I would like to really change the whole situation to make it possible to have it ratified by our Parliament.

Graeme Dobell: The threat that ratification may not happen has already brought a counter-threat from the energy giant, Woodside Petroleum, that it will not go ahead with development of the Greater Sunrise field.

East Timor is using the ratification issue to put pressure on Australia in boundary negotiations which resume in Dili this afternoon.

East Timor says that a final boundary should be set at the midpoint of the Timor Sea, half way between Australia and Timor. That would move the Greater Sunrise field from Australia's control to East Timor.

Canberra's response is that a far more favourable for Australia boundary would be drawn based on the reach of Australia's continental shelf, a determining factor in past negotiations with Papua New Guinea and Indonesia.

The Dili talks will give a clearer indication of how closely East Timor is going to tie ratification of the Greater Sunrise deal to a final border settlement with Australia.

Tanya Nolan: Foreign Affairs Correspondent Graeme Dobell.