MOSCOW — Russia has suspended delivery of nuclear materials to Iran until there is more transparency in Tehran's use of sensitive technologies, President Vladimir Putin told a visiting delegation of U.S. Jewish leaders.

Putin said Moscow would seek additional guarantees from Tehran that Russian technologies are not being used to produce weapons of mass destruction. Putin acknowledged that materials sold to Iran carry a potentially great threat of being used as weaponry because of Iran's support of terrorism.

Members of the American Jewish delegation, who soon found themselves embroiled in an ongoing rivalry within the Russian Jewish community, had no immediate reaction to Putin's pledges.

Delegation members promised Putin to work for Russia's graduation from the Jackson-Vanik amendment, a Soviet-era vestige that ties Russian trade relations with the United States to Russian Jews' freedom to emigrate.

"We will do whatever possible so that this issue in the relations between Russia and the United States is finally resolved," James Tisch, chairman of the Conference of Presidents of Major American Jewish Organizations, said after the meeting.

The Tuesday night meeting at the Kremlin ran for 2-1/2 hours and touched on an array of issues, including Russia's relations with the United States and Israel, the situation in the Middle East and the teaching of tolerance in Russian schools.

"Putin was very forthcoming, very articulate," Malcolm Hoenlein, executive vice chairman of the Conference of Presidents, said. "It was a very positive, very intensive discussion. Nobody expected it to be that long."

Other U.S. participants in the meeting said Putin took it as a serious opportunity to improve ties with the United States.

"He made it clear that rapprochement between the United States and Russia is not a tactical but a strategic goal for Russia," said Robert Meth, chairman of NCSJ, Advocates on Behalf of Jews in Russia, Ukraine, the Baltic States and Eurasia. "He underscored that this issue was his utmost priority."

The meeting took place while Israeli Foreign Minister Silvan Shalom was in Moscow for talks with his Russian counterpart.

On Monday, Shalom told Russian Foreign Minister Igor Ivanov that Israel would like to give Moscow a greater role in the peace process now that the Israeli government has endorsed the "road map" peace plan.

The Russian contribution to the peace process could be even more meaningful since Israel fears that the United Nations and the European Union — which, with Russia, helped the United States draft the plan — are being subjected to strong pro-Arab pressure.

Shalom reportedly was unsuccessfully trying to arrange a meeting with Putin. Instead, another Israeli Cabinet member, Diaspora Affairs Minister Natan Sharansky, who also is visiting Moscow this week, was supposed to take part in the discussion with the U.S. Jewish leaders.

Sharansky canceled his participation at the last minute amid media reports that Shalom was outraged when he heard about the meeting.