A small number of IOCs were invited to express interest in a closed tender for the field in August. France's Totaland Norway's Statoilhave positively responded to the request and are now awaiting access to the Azadegan field data room. Oil Ministry officials have publicly said that Russian, Chinese, Spanish and Dutch companies are also interested in the northern section of the field.

The bidding is likely to last three-six months, paving the way for a contract award by the end of 2004. The field was first put out to bid in 2000, with the Japanese consortium securing a two-year exclusive negotiating period in summer 2001. Its failure to reach an agreement by June - the expiry of the exclusivity period - was initially attributed to US political pressure, but industry sources say key financial issues had not been resolved. Nevertheless, Tokyo has directed investment of around $3,000 million to Iran in deals connected to Azadegan and is still eager to sign up for the field's development.

The 1998 discovery of Azadegan was hailed as one of the largest in recent times. The field has estimated recoverable reserves of 26,000 million barrels.

This year, Tehran announced another major heavy sour crude discovery in three fields in the south of the country. According to Tehran, the find has helped push up Iran's official recoverable reserves by 36 per cent to 130,810 million barrels, with other increases coming from improvements to existing field data. Iran has been using the rise in reserves to defend its share of OPEC production ahead of a quota realignment being discussed by the organisation.