Syrian government forces have completed the operation to "liberate" rebel-held eastern Aleppo, according to Russia's defence ministry.

At least four explosions have taken place at the location where buses were waiting to take civilians and rebel fighters from eastern Aleppo, according to reports.

Syrian state TV station Ikhbariya claimed militants had tried to take prisoners with them during the evacuation, breaching the ceasefire deal and halting the operation.

It also claimed rebels had opened fire on the convoy at a crossing point.

A military news outlet run by Hezbollah said protesters had also blocked the road being by used by the convoys, demanding the evacuation of people from two Shia villages in Idlib province.

Thousands left the besieged city on Thursday under a deal that will allow Syria's regime to take full control of Aleppo after years of fighting.

The Russian Defence Ministry said nine convoys carrying 6,400 people had left the city in the first 24 hours of the evacuation, including 3,000 rebels and 301 wounded.

All buses and ambulances were escorted by the Russian Centre for Reconciliation and members of the Red Cross, the ministry added.

Turkey put the figure of evacuees at 8,000.

Khaled Khatib, a photographer for the Syria Civil Defense - also known as The White Helmets - has posted this footage of evacuations on Twitter:

these are the last moments in Aleppo, ppl are displaced far away from their homes. our souls remain there, we will miss our city so much. 💔 pic.twitter.com/Z8S5Jp0M3P

— Khaled Khatib (@995Khaled) December 15, 2016

UN envoy Staffan de Mistura said about 50,000 people were still trapped, including 40,000 civilians.

The withdrawal began about a month after President Bashar al Assad's forces launched a major Russian-backed offensive to retake all of Aleppo.

In a video message, President Assad said the "liberation" of Aleppo was "history in the making".

US Secretary of State John Kerry said what had already happened in the city was "unconscionable", but warned over the fate of "tens of thousands of lives that are now concentrated into a very small area of Aleppo".

Four Syrian organisations have sent a UN commission a list of 304 attacks in Aleppo where they say Russia bears a "high likelihood" of responsibility for violating international humanitarian law.

Their letter to the Independent International Commission of Inquiry on Syria, obtained by the Associated Press news agency, said the attacks led to 1,207 civilian deaths, including 380 children.

It said "evidence clearly indicates that Russia has committed or been complicit in war crimes in Syria".

The evacuations were announced on Thursday, after an initial plan for civilians and fighters to leave rebel-held areas collapsed the previous day amid renewed clashes.

The UN Security Council will meet on Friday evening to discuss the crisis in response to a request by France, which is calling for international observers to be sent to monitor the situation and ensure aid deliveries.

'There can be no impunity for such grotesque crimes'

Minister for Foreign Affairs Charlie Flanagan has called the actions of the Assad regime "monstrous".

"The besieging of the population and the scale of the death, injury and destruction that is being wrought in Syria at this time is truly appalling," Mr Flanagan said in a statement. "The UN’s Commission of Inquiry has repeatedly made public the monstrous actions of the regime, publishing findings of war crimes and crimes against humanity."

The Minister reiterated his  support to the UN Security Council resolution calling for an end to the violence, and said he is determined to continue to work in support of a free and peaceful Syria.