Syria conflict: US pledges $360m in additional aid
The US has pledged to provide $364m (£276m) more in humanitarian aid to people affected by the war in Syria.
The funds, officials say, will help the UN and other charities provide food, safe water and medical care to those in the country and refugees in the region.
Meanwhile, Syrian forces have made advances in the centre of Aleppo after days of heavy air strikes, reports say.
And the World Health Organization has called for safe evacuation routes out of the city for the injured and sick.
A spokeswoman said there were only 35 doctors left to care for hundreds of trapped patients, and the number of casualties was rising.
Medical supplies were running out and there was a shortage of blood, she added.
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Russian-backed Syrian government forces launched an assault on rebel-held areas of eastern Aleppo on Thursday after a truce collapsed.
Since then, the intense and sustained aerial bombardment of Aleppo and its surrounding countryside has killed at least 248 people, almost all of them civilians, according to the Syrian Observatory for Human Rights, a UK-based monitoring group.
The US and its allies, who support the rebels fighting the Syrian government, have said the attacks constitute war crimes and accused Russia of "barbarism". Moscow has vigorously denied the allegations and criticised their "unacceptable" rhetoric.
The additional aid announced on Tuesday would bring the total US humanitarian spending for Syria to about $5.9bn (£4.5bn), the state department said.
Aleppo, once Syria's largest city and the country's commercial and industrial hub, has been divided roughly in two since 2012, with President Bashar al-Assad's forces controlling the west and rebel factions the east.
In the past year, government troops have gradually broken the deadlock with the help of Iranian-backed militias and Russian air strikes. Earlier this month, they severed the rebels' last route into the east and placed its 250,000 residents under siege.
On Tuesday, government forces were reportedly making advances in the centre of the city and also mobilising armoured vehicles and tanks.
This was the biggest assault by ground forces since the collapse of the ceasefire, Reuters reported, after several days of heavy airstrikes against rebel-held areas.
The military and the Syrian Observatory for Human Rights said the army had made some gains, but rebels disputed this, the news agency said.
At a news conference in Geneva on Monday, WHO spokeswoman Fadela Chaib said the escalation of fighting was "claiming more victims every day", and called for the "immediate establishment of humanitarian routes".
"It's a worrisome situation."
Many streets are now blocked by rubble, meaning ambulances cannot get through.
All of the 25 functioning or partially functioning medical centres are on the verge of complete destruction, according to the WHO.
Both the United Nations and the International Committee of the Red Cross have been calling for humanitarian corridors into Aleppo for several weeks, but so far those calls have been ignored, the BBC's Imogen Foulkes reports from Geneva.
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