Inpex Holdings Inc. and National Iranian Oil Co. are still in talks in Tehran over a $2 billion project to develop Iran's Azadegan oil field and the negotiations are not going to collapse, a senior Japanese trade official claimed on Thursday.

Vice Economy, Trade and Industry Minister Takao Kitabata said it is his understanding that Japan's Inpex and National Iranian Oil Co. are in tough negotiations and that the talks are likely to continue for a "very long time." He said the talks will continue because the project will benefit both Iran and Japan.

Kitabata's comments came a day after Iranian media reported that Inpex, in which the Japanese government holds a 29.35 stake, had lost its concession in the oil project, quoting Gholamhosein Nozari, managing director at National Iranian Oil.