US-backed opposition fighters have almost recaptured all of Manbij, a Syrian city northeast of Aleppo, from the Islamic State of Iraq and the Levant (ISIL).

With the support of air strikes, the Syrian Democratic Forces, or SDF, an alliance of Kurdish and Arab fighters, has taken control of 90 percent of the city from ISIL, also known as ISIS.

Manbij has been the main front in a US-led anti-ISIL coalition's ground war for months.

Al Jazeera filmed exclusive aerial footage that shows extensive damage in the city, with many homes and other buildings either partially or completely destroyed. 

Thousands of civilians manage to flee Manbij

At least 400 people have been killed in the area in the past two months.

The Britain-based Syrian Observatory for Human Rights, a group that uses a network of contacts in Syria to track the war, said at the end of July that those killed included 98 children.

Thousands of people also fled the fighting. 

Battles continue in the Sarb neighbourhood, the last ISIL stronghold.

"Daesh is finished. The town will be liberated in the coming hours," SDF fighter Ibrahim al-Hussein told the AFP news agency earlier this week, using the Arabic acronym for the group.

'Catastrophic situation' in Aleppo

The apparent victory in Manbij came as the United Nations called for urgent aid access to Aleppo, warning that civilians there were at grave risk from severe water shortages and disease after fighting intensified for Syria's second city.

Fears are growing for trapped civilians before what is expected to be an all-out battle for control of the city, a focal point of the five-year war.

Rebels and fighters loyal to Syrian President Bashar al-Assad have sent reinforcements to Aleppo in anticipation of the fighting, after opposition forces broke a government siege at the weekend and vowed to capture the entire city.

READ MORE: Battle rages in Aleppo

Hundreds of thousands of civilians remain inside Aleppo, once Syria's economic heart.

UN agencies said on Tuesday that up to two million people had gone without running water for four days, raising the risks of disease in a city already devastated by years of fighting.

UNICEF said children and families were facing "a catastrophic situation" after fighting damaged electricity networks needed to pump water.

"These cuts are coming amid a heatwave, putting children at a grave risk of waterborne diseases," said Hanaa Singer, its representative in Syria.

"Getting clean water running again cannot wait for the fighting to stop. Children's lives are in serious danger."

The UN's top humanitarian official in Syria, Yacoub El Hillo, and regional coordinator Kevin Kennedy said medical and food stocks were "running dangerously low".