In Syria, the World Health Organization is calling for medical evacuations in the embattled eastern part of Aleppo. The organisation says at least 250,000 people need treatment, and the number of injured is increasing.

"The escalation of fighting in Aleppo is claiming more victims every day. WHO is calling for an immediate establishment of humanitarian routes to evacuate sick and wounded from the eastern part of the city," said Fadela Chaib, WHO spokeswoman.

"So this is what WHO wants to do, to facilitate the evacuation of the wounded and sick from eastern Aleppo."

The spokeswoman called the situation in Aleppo "worrisome" at a news briefing in Geneva on Tuesday.

She said the encircled city is in dire need of medical and surgical supplies. Only 35 doctors and seven hospitals remain, and some of them only partially functional.

The WHO plans to evacuate the sick and injured to west Aleppo, or a hospital along the Turkish-Syrian border.