The Royal Dutch/Shell group plans to join a Japanese public-private consortium in an oil development project in Iran's biggest oil field, industry sources have revealed.

The major international oil firm and the Japanese consortium may spend more than 500 billion yen in jointly developing the Azadegan oil field, the sources said Monday.

The consortium includes Japanese oil development firm Indonesian Petroleum Ltd. (INPEX), trading house Tomen Corp. and Japan National Oil Corp.

The companies involved are currently negotiating details of the project, such as how much each company will invest and procedures for development of the oil field.

They said the companies are trying to reach an agreement before the end of this year, the deadline for the negotiations to conclude.

The Japanese government and the Japanese oil industry have been anxious to find new fields to develop since Japan's Arabian Oil Co. lost its drilling rights in Saudi Arabia's Khafji fields in February 2000. The Azadegan oil field, in southern Iran, is estimated to have up to 24 billion barrels of oil.