BEIRUT (AFP) - The United Nations sounded the alarm on Saturday about the plight of women and children in Syria's Homs, urging all parties in the conflict to enable access to some 400,000 trapped civilians.

"The situation of women and children in the Syrian city of Homs is rapidly deteriorating," UNICEF said in a statement, adding that "new checkpoints are preventing more supplies from entering" the neighbourhood of Al-Waer.

"Cannot all those involved agree that the innocent women and children in Homs, and across Syria, should be spared all possible suffering?" UNICEF's Executive Director Anthony Lake asked.

Around 400,000 civilians, mostly women and children, who were forced to flee other areas of Homs have sought refuge in Al-Waer, and are now "living in partially constructed buildings, schools and other public buildings", Mr Lake said.

But the situation there "has worsened, with reports of intense daily clashes, and rocket and mortar strikes causing many casualties", he added.

UNICEF says it and other organisations have been distributing basic supplies and ensuring access to water for civilians fleeing the fighting.

"Water and electricity is still available for now but vegetables, milk and other essentials are in increasingly short supply. Our own emergency supplies will run out within days," said the agency.

Mr Lake called on "all parties to facilitate immediate safe access to these families so we can provide life-saving assistance, and to allow those families currently trapped in Al-Waer who wish to leave to do so in safety and in dignity".

Homs has suffered some of the worst violence in Syria's 28-month conflict.

This week, government forces overran Khaldiyeh district, one of the rebels' last bastions in Syria's third city.

The army is now pressing its campaign to uproot rebels from other areas in Homs, including the central Old City district.

The UN says more than 100,000 people have been killed in Syria's war, most of them civilians.

Millions more have been forced to flee their homes, about 75 percent of them women and children.