The United Nations headquarters building, New York, US, August 15, 2014. REUTERS/Carlo Allegri/Files

UNITED NATIONS: The United States has requested a UN Security Council (UNSC) emergency meeting on the deadly unrest in Iran to be held on Friday, diplomats said.

Washington asked that the meeting be scheduled at 3:00 PM (2000 GMT) to discuss the protests that began on December 28.

Russia has criticized the US push for Iran to be discussed at the UNSC and it remained unclear if other council members would try to block the meeting.

Diplomats said Thursday there could be a request from Russia or from other countries to hold a procedural vote ahead of the meeting.

For a new agenda item to be discussed at the UNSC, at least nine of the 15 council members must support holding the meeting.

No vetoes apply.

US Ambassador Nikki Haley said earlier this week that she would be seeking a meeting of the top UN body to show support for demonstrators.

"The people of Iran are crying out for freedom," Haley said Tuesday. "All freedom-loving people must stand with their cause."

At least 21 people have died and hundreds have been arrested as protests over economic woes turned against the government in Tehran, with attacks on government buildings and police stations.

Haley said she would also ask the UN Human Rights Council in Geneva to discuss the violence.

The US requested that there be an open meeting on Iran at the council chamber and that a UN official from the political affairs department present a briefing on the violence.

In Moscow earlier, Russia's Deputy Foreign Minister Sergei Ryabkov warned the United States against "any attempt to interfere in the internal affairs" of Iran.

Russia maintains that the protests do not pose a threat to international peace and security and should not be taken up by the Security Council.

On Thursday, there were large pro-regime rallies in Iran, with state TV showing huge crowds marching in support of the government across 10 cities.

The US imposed unilateral sanctions on five Iranian companies linked to Tehran's ballistic missile program.