The World Health Organisation and the Red Cross have called for dozens of sick and wounded people in the embattled Syrian city of Aleppo to be evacuated safely for treatment.
The Syrian military, helped by Iranian-backed Shi'ite militias and the Russian air force, launched a campaign to take rebel-held eastern Aleppo last week, where the WHO said only 35 doctors remained to care for more than 250,000 people.
Syrian pro-government forces attacked the opposition-held sector of Aleppo on several fronts on Tuesday, the biggest ground assault yet in a campaign that has destroyed a US-backed ceasefire.
"WHO is calling for the immediate establishment of humanitarian routes to evacuate sick and wounded from the eastern part of the city," WHO spokeswoman Fadela Chaib said.
Only seven hospitals remain in east Aleppo, some of them only partially functional, and hundreds of wounded are trapped in the encircled city, she said.
WHO spokesman Tarik Jasarevic said that dozens of patients required evacuation and that local health authorities would draw up the initial list which then would be assessed by the Syrian Arab Red Crescent.
"WHO submitted the request for medical evacuations through the Ministry of Health to the Ministry of Foreign Affairs," Jasarevic said by email from Syria. "The plans are being firmed up on how and where to evacuate with options of west Aleppo and Bab al Hawa hospital in Idlib," he said, referring to a hospital along the Turkish-Syrian border.
Medical staff in eastern Aleppo are working relentlessly to save lives but are unable to cope with the demand for specialised and emergency services, ICRC spokeswoman Krista Armstrong said.
"There is a desperate need for medical evacuations; hospitals are short of surgical trauma items and blood products for transfusions," she said.
Syrian doctors said on Monday they were in dire need of medical and surgical supplies to treat hundreds of wounded.
The Syrian doctors said at least 40 wounded people in eastern Aleppo needed to be evacuated, but most wanted to be sent to rebel-held areas or abroad, not to the government-controlled western side of the city.
"We are waiting to evacuate them safely, to the hospitals in Idlib governorate, and some of them need to be evacuated to Turkey," said Dr Abd Arrahman Alomar of the Syrian American Medical Society (SAMS).
Jessy Chahine, spokeswoman for UN Special Envoy for Syria Staffan de Mistura, told Tuesday's briefing: "We do remind always all parties that evacuation operations have to be in accordance with IHL [international humanitarian law] and protection standards."
International law has rules against forcibly displacing people and evacuations must be voluntary, she said.