The fields, with a combined estimate of 0.8 trillion cubic feet of gas and eight million barrels of condensate, are controlled by Woodside which has 55% of the Geographe field and 50% of the Thylacine field.

Woodside managing director John Akehurst said: "Development of Geographe and Thylacine will provide a secure, alternative and competitive gas supply to south-eastern Australia. It is an important building block in Woodside's strategy to establish a significant gas business in eastern Australia," he said.

"As operator of the Geographe and Thylacine fields, we will now be making development proposals to the joint ventures with the intention of starting gas deliveries in 2006."

The agreement is conditional on Woodside obtaining government and joint venture approvals for the development of Geographe and Thylacine which are between 55km and 70km south of Port Campbell on the Victorian coast.

In late July, the joint ventures announced the start of environmental assessment of development options for both fields under Commonwealth and Victorian legislation.

Woodside operates VicP43 (Geographe) and T30P (Thylacine) on behalf of joint ventures that include Origin Energy Resources Limited, CalEnergy Gas (Australia) Limited and Benaris International NV.