"At this stage BHPB is not involved in this project and any future role will depend on further discussions with NIOC," commented a BHPB spokesman.

On Wednesday, Iranian state television reported a buy-back deal had been finalised with private Iranian energy company Petro Iran to renovate the offshore Foroozan-Esfandiar oilfields, boosting output from 40,000 barrels of oil per day to 109,000 bopd in three years.

Iran designed the buy-back deals to skirt a constitutional ban on foreign investment through production-sharing deals. The buy-back allows foreign firms to recoup investment and get a profit by receiving part of the project's output.

Production in the fields, which are shared by Iran and Saudi Arabia has tailed off in recent years and many analysts believe Petro Iran will look to BHPB to provide the financial muscle to develop the fields.

Late last year, BHP Billiton Petroleum president Mr Phil Aiken in a briefing to the investment community said that the company was in advanced discussions regards participating in the project.

"We have been in discussions with Iran for some time about buy-back opportunities and we are currently at an advanced stage of discussion over the rejuvenation of the Foroozan field to enhance production levels," Mr Aiken said.

"This project could be BHP Billiton Petroleum's first project in Iran and with our excellent relationships could be the significant platform on which to build further growth."

Iran has about nine percent of the world's proven oil reserves and about 16 percent of the world's gas reserves and was of major interest to BHPB, which is one of the companies currently involved in a consortium in a study on how to best use gas from Iran's huge South Pars field over the next 25 years.