ALEPPO: Rebels in Aleppo called for a five-day truce and the evacuation of civilians on Wednesday after losing more territory including the Old City to a Syrian army of fensive.

Heavy fighting in the city stoked mounting international concern, with six Western powers urging a ceasefire and UN chief Ban Ki-moon describing the plight of civilians as `heartbreaking`.

US Secretary of State John Kerry was to hold fresh talks with Russian counterpart Sergei Lavrov in Hamburg, Germany, later on Wednesday on efforts to halt the fighting.

A blistering new offensive launched last month has seen President Bashar al-Assad`s forces move closer than ever to retaking all of Aleppo and winning their most important victory yet in the civil war that began in 2011.

Rebel fighters, who took control of east Aleppo in 2012, have suf fered a string of defeats in recent days, losing about 80 per cent of their former territory in the city, according to the Syrian Observatoryfor Human Rights.

Regime forces scored another important victory on Wednesday when the rebels retreated from the Old City, the historical heart of Aleppo, said the Observatory, a Britain-basedmonitor.

Increasingly cornered in a sliver of territory in the city`s south-east, rebel factions issued a joint statement calling for an `immediate fiveday humanitarian ceasefire`. The statement also called for `the evacuation of civilians who wish to leave` the city`s east to rebel territory in northern Aleppo province.

The statement from the six Western powers Britain, Canada, France, Germany, Italy and the United States said a humanitarian disaster was `taking place before our very eyes` in Aleppo. `The urgent need now is for an immediate ceasefire to allow the United Nations to get humanitarian assistance to people in eastern Aleppo.

It lashed out at the regime in Damascus and its `foreign backers, especially Russia,` accusing them of blocking emergency help.UN chief Ban also appealed for a ceasefire, saying in Vienna: `What we have seen most recently in eastern Aleppo, that is really heartbreaking.The assault has prompted a mass exodus of east Aleppo residents and the Observatory said on Wednesday that at least 80,000 had now fled their homes.-AFP