Saarar Azadi, left, of Brooklyn, N.Y., is comforted by a fellow demonstrator who would not give her name as they sing the Iranian song “My Childhood Friend” during a rally in New York against the Iranian government as part of the “Global Day of Action” protests Saturday. Protesters across the world called on Iran Saturday to end its clampdown on opposition activists, demanding the release of hundreds rounded up during demonstrations against the country’s disputed election.

London ? Protesters across the world called on Iran Saturday to end its clampdown on opposition activists, demanding the release of hundreds rounded up during demonstrations against the country’s disputed election.

Groups including Human Rights Watch and Amnesty International backed a global day of action, with protests planned in more than 80 cities.

The protesters want Iranian authorities to release what they say are hundreds, or even thousands, of people detained during protests that followed the presidential election last month that returned Mahmoud Ahmadinejad to power.

Inside Iran, as well, Iranian police and pro-government militia attacked and scattered hundreds of protesters who had gathered in Tehran in response to the global demonstrations of solidarity, witnesses said.

Demonstrators in Vanak and Mirdamad districts chanted “death to the dictator” and “we want our vote back” before they were attacked and beaten by police Saturday. The witnesses spoke on condition of anonymity for fear of retaliation.

Supreme Leader Ayatollah Ali Khamenei has declared Ahmadinejad’s victory valid.

Police said about 600 protesters joined a “noisy but peaceful” demonstration, outside the Iranian embassy in London, one of a series of events in cities across Europe. In Brussels, Belgium, protesters held placards carrying images of the detained or dead, including Neda Agha Soltan, the 27-year-old whose death — beamed around the world on the Internet — became a rallying cry for opponents of the regime.

In Amsterdam, several hundred people watched Iranian Nobel Peace prize laureate Shirin Ebadi urge the international community to reject the outcome of the Iranian election and called for a new vote monitored by the United Nations.

Several hundred protesters gathered behind police barricades just off Times Square in New York City. One man hoisted a green placard, splattered with red, that read, “Where is my vote?” The crowd chanted, “Stop the killing. Stop the torture.” A small group of Iranians in New York have been on a three-day hunger strike and are holding frequent demonstrations outside the United Nations to call on the world body to investigate human rights abuses in Iran.

In Washington, hundreds of demonstrators were marching from a U.N. office downtown to the National Mall for a rally.

About 80 people wearing headbands, wristbands or bandanas in green — the color of Iran’s protest movement — demonstrated in front of the U.N.’s European headquarters in Geneva, while several hundred people staged a rally at Paris’ Trocadero square overlooking the Eiffel Tower.

“We’ve had enough of religious regimes that don’t have the Iranian people’s best interest at heart,” said protester Sakineh Davoodi, a 50-year-old cashier from Iran who has lived in France for 23 years.

About 350 people gathered in downtown Vienna, and about 150 protesters gathered in Rome. In Norway, about 250 Iranian emigres met at a conference center on the outskirts of Oslo, and about 3,000 people gathered in Stockholm and others in Copenhagen, Denmark.