Iranian diplomat Ramin Mehmanparast is escorted from the street near the United Nations headquarters in New York (AP/Monica Gutierrez)

An Iranian diplomat was escorted from a Manhattan street by police after he was surrounded and threatened by angry protesters near the United Nations headquarters.

Deputy foreign ministry spokesman Ramin Mehmanparast was walking near the building when he was spotted and confronted by the mob on Second Avenue near East 48th Street, said New York Police Department spokesman Paul Browne.

He flagged down police officers, who helped him get to a safe spot. Mr Browne said the threats were believed to have been verbal.

The incident followed a speech by Iranian president Mahmoud Ahmadinejad to the UN General Assembly. Outside the building, thousands of anti-Ahmadinejad demonstrators rallied in Dag Hammarskjold Plaza opposite the world body.

Mr Ahmadinejad, known for past fiery denunciations of the United States and Israel, said before the General Assembly that there was a "continued threat by the uncivilised Zionists to resort to military action against our great nation".

Outside, former US House of Representatives speaker Newt Gingrich, who ran for president earlier this year, challenged President Barack Obama to take stronger action against Iran as it threatens to become a nuclear power. But he praised the Obama administration for recently taking the Iranian dissident group Mujahedeen-e-Khalq, or MEK, off the US terrorist watch list. The group is a major anti-Ahmadinejad force that was allied with Saddam Hussein in the 1980s.

A coalition of Iranian-American groups organised the protest against Mr Ahmadinejad - one of the largest gatherings staged against the Iranian leader in recent years during the General Assembly.

Speakers included high-profile US politicians including two former US ambassadors to the UN, Democratic congresswoman Carolyn Maloney and former congressman Patrick Kennedy.

Protesters wore yellow vests with photos of people they say were massacred. One sign read: "Fallen for Freedom in Iran."

In a text message, Alireza Miryusefi, a spokesman for Iran's UN Mission, blamed the aggression of the protesters towards Mr Mehmanparast on the MEK. The "MEK is going to be delisted and you can expect such a aggressive behaviour of a terrorist sect. It would be another wrong step by US administration. The responsibility of protecting all diplomats is on behalf of government of USA", Mr Miryusefi said.

PA