Fumio Kishida was set to leave Tokyo overnight today for a meeting with his Iranian opposite number tomorrow, along with a courtesy call on moderate president Hassan Rouhani.
Iranian Foreign Minister Mohammad Javad Zarif, who has been in talks with the so-called P5+1 in Geneva, said on today it may be possible to reach a deal that could see Tehran freeze its disputed nuclear programme in exchange for relief from crippling sanctions.
"As this window of opportunity is open for only a limited period, Iran should proactively show flexibility to solve the problem and restore trust among the international community," he said.
Western powers suspect Iran's uranium enrichment programme is part of a plan to develop nuclear weapons. Tehran denies this and insists it is entirely peaceful.
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Iran is anxious for relief from crippling economic sanctions that have cut oil revenues by more than half, caused the value of the rial to plunge and pushed inflation above 40 per cent.
Japan, which is heavily dependent on Middle Eastern oil, has maintained friendly relations with Iran through its years of ostracism, keeping up a diplomatic two-way that many developed countries cut off decades ago.
But since Rouhani took office in August hopes have been raised of an end to the long-running crisis, especially after a round of hectic diplomacy during the UN General Assembly in September.