Staff writer In a move apparently reflecting the rapidly warming atmosphere surrounding bilateral relations, Iran has asked Japan to provide some 5 billion yen in fresh official yen loans for a project to reduce air pollution, government sources said Wednesday. The sources said the oil-rich Persian Gulf state, which is experiencing increasingly acute air pollution problems due to motor vehicles emissions, wants to use the new yen loans to establish a network of pollution monitoring facilities at 28 sites across the nation. The sources said, however, that Tehran has not yet given Tokyo further details of the project, but that the Japanese side is considering the request. Japan is expected to make a decision on the request before President Mohammad Khatami visits Tokyo. The trip will be Khatami's first to Japan and is expected by the end of this year. Japan's provision of loans to Iran is a diplomatically sensitive matter because the United States, Japan's most important ally, still regards Iran as a rogue state and objects to any such aid. It is also unclear whether -- and how -- a Japanese decision on the request will be affected by reports that the Iranian Embassy in Tokyo may have been involved in the illegal export of Japanese anti-tank sighting devices to Iran. Iran is a major supplier of crude oil to Japan, which relies heavily on the Middle East for its petroleum needs. Diplomatic relations between Japan and Iran have improved significantly since the end of 1998, when Kamal Kharazzi became the first Iranian foreign minister to visit Tokyo in nearly 11 years. Then Foreign Minister Masahiko Komura also visited Tehran last summer, becoming the first Japanese foreign minister to do so in nearly eight years. In a meeting with Khatami, Komura asked the Iranian leader to visit Tokyo by the end of this year. Khatami accepted the invitation.Khatami, a liberal cleric and staunch advocate of greater political and religious freedom, won a surprise landslide victory over Nateq-Nouri, a candidate backed by the country's conservative leaders, in a presidential election in May 1997. If Khatami comes to Tokyo, he will be the highest-ranking Iranian to do so since the 1979 Islamic Revolution. During his trip to Tehran, Komura, in an apparent change in Tokyo's Iranian aid policy, also pledged to provide about 7.5 billion yen in additional yen loans for a hydroelectric power project on the Karun River in southern Iran. In May 1993, Japan lifted a nearly 18-year-old freeze on fresh official yen loans to Iran, providing 38.6 billion yen as the first of three planned installments totaling some 160 billion yen for the power project. Under considerable pressure from the U.S. administration of Bill Clinton, however, Japan delayed disbursement of the second tranche of yen loans, worth about 48 billion yen, that was originally planned for 1994. Japanese officials insist that the additional loans of about 7.5 billion yen do not mean a full-scale resumption of yen loans for the power project because they are simply to fill a spending gap for the first phase of the project, which was originally supposed to be completed with the first loan installment. The Clinton administration has pursued a policy of "dual containment" against Iran and Iraq since early 1993, accusing Iran of sponsoring terrorism, sabotaging the Middle East peace process, developing weapons of mass destruction and abusing human rights. Tehran has vehemently denied the charges. Since its inauguration in the summer of 1997, the Khatami administration has steadily improved ties with European countries as well as with Iran's neighbors. Khatami visited Italy and France last year. In early January, Iranian Foreign Minister Kharazzi visited Britain, the hitherto most vocal critic of Tehran after the U.S. among the major industrialized countries.