Iran's foreign minister said Tuesday he has been informed by UN chief Antonio Guterres that Washington has denied him a visa for a trip to UN headquarters in New York.
"What we know is that the US State Secretary (Mike Pompeo), in a call to the Secretary General of the United Nations, said: 'We did not have time to issue a visa for Mohammad Javad Zarif and we will not issue a visa'," Zarif said.
"The Secretary General responded by saying that it is Iran's right to take part in this session," Tehran's top diplomat said, quoted by semi-official news agency ISNA.
Asked about Zarif's complaint, Pompeo said the State Department does not comment on visa matters.
"I will say only this -- we will always comply with our obligations under the UN requirements and the Headquarters Agreement, and we will do so in this particular instance and more broadly every day," he told reporters.
Zarif was speaking to reporters in Tehran at a gathering to promote an Iranian peace plan for the Gulf.
His remarks came as Iran held funeral processions on Tuesday for one of its top military commanders killed in a US drone strike in Iraq.
Zarif later took to Twitter, saying the rejection violated the terms of a 1947 agreement on the travel of representatives of UN members to and from the headquarters.
But he said "denying me a visa... pales in comparison to" US sanctions and threats, as well as the "cowardly assassination" of Iranian general Qasem Soleimani last week.
"What are they really afraid of? Truth?" he tweeted.
Soleimani's killing in the US strike Friday in Baghdad has sparked a war of words between the arch-foes, with Iran vowing "severe revenge" and US President Donald Trump threatening to hit back hard for any retaliation.
Trump warned on Saturday that Washington had lined up 52 targets if Tehran attacked US personnel or assets.
Zarif said the US visa decision was "a sign of the bankruptcy of the US government and Trump's regime", according to ISNA.
The Iranian foreign minister said he had been planning to go to UN headquarters on Thursday for an open debate on "Upholding the Charter of the United Nations".
But he added that he had also intended to "raise America's crimes" during his visit to New York.
It is not the first time that Iranian officials have encountered problems when travelling to New York for events at UN headquarters.
In December, the UN General Assembly called on the United States to lift restrictions on Iranian diplomats.
Since mid-2019, Iranian diplomats and ministers have been under strict movement restrictions when they are in the United States.
They are limited largely to the area around UN headquarters, the Iranian diplomatic mission and the ambassador's residence.
In September, while taking part in the annual General Assembly, Zarif complained he was unable to visit the country's UN ambassador in a US hospital.