United Nations Headquarters
United Nations HeadquartersThinkstock

The United Nations voiced concern on Monday after the United States imposed unusually harsh restrictions on the movements of Iran's Foreign Minister, Mohammad Javad Zarif, who was visiting the world body in New York, AFP reports.

Secretary of State Mike Pompeo told The Washington Post that the US had issued Zarif a visa but forbade him from moving beyond six blocks of Iran's UN mission in Midtown Manhattan.

"US diplomats don't roam around Tehran, so we don't see any reason for Iranian diplomats to roam freely around New York City, either," Pompeo told the newspaper.

"Foreign Minister Zarif, he uses the freedoms of the United States to come here and spread malign propaganda," he added.

UN spokesman Farhan Haq told reporters that the UN Secretariat was in contact with the US and Iranian missions about Zarif's travel restrictions and "has conveyed its concerns to the host country."

The United States, as host of the United Nations, has an agreement to issue visas promptly to foreign diplomats on UN business and only rarely declines.

Washington generally bars diplomats of hostile nations from traveling outside a 40-kilometer (25-mile) radius of New York's Columbus Circle.

Zarif is scheduled to speak Wednesday at the UN Economic and Social Council, which is holding a high-level meeting on sustainable development.

Treasury Secretary Steven Mnuchin said on June 24 that Zarif would be blacklisted as part of sanctions targeting Iranian leaders announced by President Donald Trump.

Last week, however, officials said the US has decided not to sanction Zarif for now, leaving open the possible of future negotiations with the Islamic Republic.