US Secretary of State Mike Pompeo on Wednesday said American and partner forces seized a boat carrying Iranian weapons to Houthi rebels in Yemen, and renewed his call for the UN Security Council to extend an arms embargo on Iran.
"The Security Council must extend the arms embargo on Iran to prevent further conflict in the region," Mr Pompeo said.
"No serious person can possibly believe Iran will use any weapon it receives for peaceful ends."
He is leading a US drive to persuade the Security Council to extend the embargo, which is due to expire in mid-October.
The expiry is in the terms of the 2015 nuclear deal, from which the US withdrew in 2018, between Tehran and world powers.
Last week Mr Pompeo took his appeal to the council, addressing its 15 members.
But Russia and China, who hold the power of veto, indicated their opposition to an extension.
On Wednesday, Mr Pompeo said US and "partner" forces intercepted the vessel, which was carrying Iranian arms to the Houthis, off Yemen's coast on June 28.
"Iran is not abiding by the UN arms embargo that is due to expire in less than four months now," he said.
Mr Pompeo said the weapons included 200 rocket-propelled grenades, more than 1,700 assault rifles, 21 surface-to-air missiles, land missiles, anti-tank missiles "and other advanced weapons".
The Iran-backed Houthi rebels have been fighting the Yemeni government, backed by a Saudi-led Arab Coalition, since 2015.
Mr Pompeo said a report by US Secretary General Antonio Guterres last week confirmed US that weapons seized by US forces in November 2019 and February 2020 were "of Iranian origin".
Iran’s mission to the UN said there were “serious flaws, inaccuracies and discrepancies” in Mr Guterres's report.