The US Secretary of State John Kerry on Thursday accused the Assad regime and its allies, Russia and Iran, of carrying out "nothing short of a massacre" in Aleppo. 

As thousands of Syrian civilians prepare to evacuate the city's final rebel-held enclaves following a temporary truce agreement, Kerry told reporters that the US was seeking an immediate and durable cessation of hostilities in Aleppo.

"There is absolutely no justification whatsoever for the indiscriminate and savage brutality against civilians shown by the regime and by its Russian and Iranian allies over the past few weeks, or indeed over the past five years," he said. "We are seeing the unleashing of a sectarian passion."

With the Obama administration in its waning weeks, Kerry's outgoing message was for the international community to exert pressure on all parties involved in the conflict.

Merkel: Aleppo crimes cannot go unpunished

Meanwhile, German Chancellor Angela Merkel spoke out strongly against Russia and Iran for their support for the Syrian regime during the Aleppo onslaught.

Speaking at Thursday's EU summit in Brussels, she said the two countries were directly responsible for crimes committed against the Syrian population; crimes that she said could not go unpunished.

Meanwhile, Germany's foreign ministry called on Syrian President Bashar al-Assad and his allies to guarantee the safety of civilians by allowing humanitarian aid into the region - a call widely echoed at the summit.

"The responsibility lies with Damascus, Moscow and Tehran," the ministry said in a statement. "We will not look away. There was never any justification for the destruction of Aleppo. However, now the focus is on saving human lives."

Evacuations out of Aleppo begin

The first group of evacuees left the eastern, rebel-held areas of Aleppo on Thursday under a deal brokered between Russia, Assad's main coalition ally, and Turkey, a leading backer of rebel forces.

The first evacuation convoys carried some 3,000 civilians and over 40 wounded people to the nearby rebel-held Idlib province.

 A convoy of 13 ambulances with wounded civilians also left the last rebel-held part of the city on Thursday. Later on Thursday, Syrian state TV said a second convoy of 15 buses had left for the countryside.

However, some 50,000 people, including 40,000 civilians, remained trapped in the city, according to the UN peace envoy for Syria, Staffan de Mistura. A further 1,500 to 5,000 rebel fighters and their families were also still in Aleppo.

The evacuation and temporary truce effectively surrenders the city to the Syrian government after years of fighting.

The fall of Aleppo marks Assad's biggest victory in the devastating, nearly six-year-long civil war. Assad described the "liberation" of Aleppo as "history in the making."

dm/rc (Reuters, AP, AFP)