Brita Hagi Hasan told European Union leaders Thursday this was the "last opportunity for humanity" in east Aleppo, as Syrian President Bashar al-Assad celebrated his takeover of the formerly opposition-held city as "historic." Hasan is the president of the Aleppo city council, referred to as its "mayor," who's been living outside Syria since being wounded there in July. Saying the international community had failed to prevent the violence against his people, Hasan now pleaded for international monitors to observe the on-again, off-again evacuation he doesn't trust.

Norwegian diplomat Jan Egeland, chair of the UN's Task Force on Humanitarian Access in Syria, confirmed that the UN's priority is to first evacuate the sick and wounded, and especially, to get children "out of the Aleppo crossfire." He expressed concern that ongoing disputes between the rebel and government sides could derail the operation, tweeting that the "window we have now we may never get again."

Speaking through an interpreter outside EU headquarters, Hasan noted the first convoy of civilians leaving Thursday in government buses had been shot at and people wounded, including two rescuers from the civilian-run "White Helmets" group. "We demand a more serious ceasefire," Hasan told journalists a short distance from European Council headquarters. "We should not be negotiating on the blood of people."

Hasan had come to Brussels at the suggestion of the French government, but not knowing what kind of reception he'd get from EU leaders. However, European Council President Donald Tusk invited Hasan to meet him, and then to speak to the heads of state and government. Hasan said he told the 28 that while the UN had failed to stop the violence in Syria, he's calling again for UN assistance now to implement a "real active role...with monitors on the ground and supervision of the evacuation of civilians".

He says Syria needs a "real implementation of the rule of law" and an end to the violence he said has destroyed "not only people but even the stones, the buildings and trees in my country." Hasan also wants examination of the evidence of war crimes committed by the Syrian regime, which he says is already in the hands of the UN Security Council.

Tweeting after Hasan's appearance, Finnish Prime Minister Juha Sipila called it a "strong appeal." Sipila echoed the councilman's demands that the Syrian government allow humanitarian assistance in.

EU foreign policy chief Federica Mogherini said she was using all her influence to stabilize the situation, phoning the Iranian foreign minister and publicly urging the Russian government to "uphold their responsibilities and protect civilians in these hours."

Heading into the meeting, Mogherini called the plight of Aleppo residents "completely unacceptable."

EU leaders wrapped up their summit many hours late, giving short shrift to the scheduled discussion on Brexit. "We are not indifferent to the suffering of the Syrian people," Tusk said, noting that "all European diplomats" are working very hard on it. On behalf of the EU, Tusk demanded "full and unrestricted access for all medical personnel and aid workers." He said he'd be using all EU pressure on other states who are present in Syria.

"It's impossible to stop this conflict by force," Tusk said, noting nonetheless that the parties which had been most "effective" in Syria were not those looking for a diplomatic solution, but rather the Russians who led their bombing campaign against the Aleppo opposition.

Meanwhile, Brita Hagi Hasan said outside, "Every moment in Aleppo is a bloodbath."