China’s CNPC has signed a deal with Iran’s National Iranian Oil (NIOC), promising to pay 90% of development costs for the South Azadegan oil field while taking ownership of a 70% stake, according to Iranian news sources.

Although no financial terms have been disclosed, managing director, oil engineering and development of NIOC Naji Sadouni said that the project needs investment of up to $2.5bn, adding that it could produce 260,000 barrels of oil per day, Reuters reported.

Japan’s Inpex holds 10% of the oil field, Shana reported in a newsletter dated 29 July, citing Sadouni, according to Reuters.

But a CNPC manager based in Beijing told Reuters on Friday that the Memorandum of Understanding (MOU) was actually signed in early spring of this year and that the two sides had made no significant breakthrough in the negotiation since then.

Last month the Iranian media also reported that CNPC had signed a $4.7bn deal with NIOC to develop phase 11 of the South Pars gas field, though CNPC officials have kept quiet on the details of the deal.