Japan will be in sync with the five permanent members of the U.N. Security Council should they decide to bring the Iranian nuclear case up for discussions, Foreign Minister Taro Aso suggested Tuesday.

Aso said at a news conference that he told visiting Iranian Foreign Minister Manouchehr Mottaki on Monday that "Japan has had a long relationship with Iran, but if (Iran will) antagonize the entire Security Council, there is a limit" to what Japan can do in trying to help avert a crisis.

Aso said he renewed his call for Iran to accept a Russian compromise proposal, saying, "There is a need for you to study this some more."

Iran and Russia reached an agreement in principle Sunday to set up a joint uranium enrichment venture in a move that is hoped will defuse current tensions ahead of a key International Atomic Energy Agency meeting next Monday.

Moscow's offer to enrich Iran's uranium on its soil is seen as a last-ditch diplomatic effort ahead of the IAEA meeting, which could pave the way for the international community to impose sanctions on Iran.

Mottaki met trade minister Toshihiro Nikai in the morning and agreed an oil development project in Azadegan is important for both countries.