ANKARA (AFP) - Hundreds marched through Ankara on Thursday (Dec 15) in protest at Russian and Iranian involvement in the siege of Aleppo, the latest in a series of demonstrations in Europe over the Syria crisis.

Up to 800 people joined the demonstration, with some chanting "Aleppo is the world's shame" outside the Iranian embassy before protesting at the Russian embassy.

Protesters held flags of the Syrian opposition as well as placards saying: "Massacre in Aleppo, theatre at the UN", according to an AFP photographer at the scene.

A day earlier, more than 1,000 people had gathered outside the Iranian consulate in Istanbul to demonstrate over what they said was a "massacre in Aleppo".

Turkey has provided support to the Syrian opposition and repeatedly called for Assad to go.

Protests have been staged in several European cities as the horror in Aleppo has unfolded, with reports of atrocities including summary executions.

On Wednesday (Dec 14) night, Danish police said as many as 7,000 people braved freezing temperatures in Copenhagen to protest against the operations in Syria.

"I'm here tonight to show my (solidarity) with the Aleppo people. And this is the only thing I can do," Calle Henriques, a retired restaurateur, told AFP.

Two banners reading "Save Aleppo" and "Stop the killing" were hung on a stage where speakers and performers were standing, as hundreds of demonstrators carried torches handed out by the protest's organisers.

Several hundred marched in Paris and the lights of the Eiffel Tower were switched off to show support for the people of Aleppo.

And several thousand marched in Sarajevo, which itself suffered the longest siege in modern times being pounded by Bosnian Serb forces for 43 months during the 1992 to 1995 war.

On Thursday, 25 NGOs providing humanitarian support to over five million Syrians issued a statement condemning the international community over its "hollowness, inefficacy, and moral bankruptcy" in Aleppo.

Organisations including the Syrian American Medical Society urged the international community to "insist on independent observers (the UN or other external actors) to be present" for civilian evacuations from Aleppo.

Hundreds of civilians and rebels left Aleppo on Thursday under an evacuation deal brokered by Turkey and Russia with the opposition in eastern Aleppo earlier this week.