TEHRAN (Kyodo) Iranian Oil Minister Kazem Vaziri-Hamaneh said Wednesday his government is willing to negotiate with Inpex Corp. beyond the Sept. 15 deadline it set to finalize a $2 billion deal to develop the giant Azadegan oil field, according to a report by the Reuters news agency.

"We are intending to continue the negotiations," Reuters quoted Vaziri-Hamaneh as telling reporters in Vienna.

Asked if Sept. 15 deadline was final, the Iranian oil minister said it was not.

Iran warned Japan last month that it might seek to develop Azadegan with a Russian or a Chinese partner if a deal with Japan was not reached by mid-September, because of concerns over delays by Inpex, which holds the concessions for the development of the oil field in southern Iran, an Iranian news agency reported earlier.

Iran apparently believes Japan is deliberately delaying the project due to pressure from the United States, which opposes Iran's nuclear development program and is trying to impose international sanctions on Tehran.

Inpex is partially owned by the Japanese government.

The firm said it has not yet started developing the field, in part because the area still has mines from the Iran-Iraq War that ended in the early 1990s.

The Azadegan oil field is one of the world's largest, with estimated crude oil reserves of 26 billion barrels.

Inpex's Iranian partner, an affiliate of National Iranian Oil Co., is in charge of negotiating with Japanese firms. The NIOC and Inpex signed a deal to develop the field in February 2004.