Iran's foreign minister has rejected calls by Japan to end its uranium enrichment program, despite international suspicion that the Islamic Republic may be secretly attempting to produce nuclear weapons. Japanese Prime Minister Junichiro Koizumi apparently failed to obtain any concessions from the Iranian foreign minister.

Japanese media say Prime Minister Junichiro Koizumi told Iranian Foreign Minister Manouchehr Mottaki he hopes Tehran will take measures to win international trust over its nuclear plans.

Mr. Koizumi's attempt at mediation, during a 30-minute meeting, came after the International Atomic Energy Agency issued a new report, based on three years of inspections, saying it cannot determine if Iran is trying to develop nuclear weapons.

The European Union and the United States suspect that nuclear weapons are Tehran's goal.

But Japanese government officials say Mottaki repeated Iran's standard response, that Tehran has the right to use nuclear power for peaceful purposes. He also invited Japanese foreign investment in up to 15 atomic plants in Iran.

The IAEA's board will meet next week to discuss referring Iran to the U.N. Security Council for possible sanctions.

Japanese Foreign Ministry Spokesman Tomohiko Taniguchi says officials in Tokyo tried to convince Mottaki that the IAEA report is a clear signal that time for Iran to act is running out.

"That indicates that [the] clock is ticking, before this issue is going to be moved on to the next stage," he said. "So now is the time for the Iranian side to really have a sense of urgency."

Japan's foreign minister, Taro Aso, earlier met with Mottaki for three hours. He indicated that if the Security Council decides to take up the Iranian nuclear issue, Japan is likely to go along with the council's five permanent members. Four of those members have indicated that they would support sanctions against Iran.

Aso told reporters he had informed Mottaki that despite Japan's long relationship with Iran, if Iran antagonizes the entire Security Council, there is a limit to what Tokyo will do in trying to avoid a crisis.

Aso also said he reiterated his call for Iran to accept a Russian offer to enrich Iran's uranium on Russian soil. Mottaki reportedly told Aso that talks between Tehran and Moscow on that offer are set to continue.

The Russian proposal would allow greater international supervision of Tehran's nuclear activities.

But Japanese Foreign Ministry officials say Mottaki insisted Iran would never abandon its uranium enrichment work, which Tehran insists is only meant to generate electricity.

Japanese officials say they are hoping that quiet diplomacy by Tokyo and Moscow can avert a crisis. They say Japan and Russia are trying to stress to the Iranians the benefits they could reap if they gave up uranium enrichment, compared with statements from Washington and European capitals stressing the consequences of non-compliance with IAEA rules.