Syrian regime forces on Friday launched a new offensive in Aleppo as the government, backed by Russian air power, tries to tighten the noose around rebels in the area, activists said.
The attack is targeting the north-eastern parts of Aleppo, which have seen an intense military campaign against the opposition-controlled areas in recent weeks, they said.
Local activist and cameraman Mahmoud Rslan told dpa that rebels foiled attempts by the regime to advance mainly in the opposition area of Suleiman al-Halabi in eastern Aleppo, home to the main water plant that supplies Aleppo with water.
Heavy bombing on the facility has put it out of operation, Ahmed Baroudi of Save the Children said.
"Most water pipes in eastern Aleppo have also been destroyed. There is no capacity to repair them," he told dpa.
Forces of Syrian President Bashar al-Assad started a ground attack against rebels in north-eastern Aleppo on Friday, a Syrian military source said.
The launch pad for the offensive is the Handarat refugee camp that the government forces recaptured from the rebels on Thursday, the source added.
Handarat, a Palestinian refugee camp, is located near Castello Road, a major supply route to opposition areas in eastern Aleppo.
An estimated 300,000 people in eastern Aleppo are under siege by government forces.
Residents there report declining supplies of basic goods, including food, electricity and medicine.