UN envoy Staffan de Mistura has held talks in the Syrian capital to try to finalise a deal to freeze fighting in the war-ravaged northern city of Aleppo.

De Mistura met Foreign Minister Walid Muallem and agreed to send a delegation from his Damascus office to Aleppo on a fact-finding mission, state news agency SANA said, without giving a date.

De Mistura's visit started as the army and pro-goverment fighters regained territory in southern Syria from forces opposed to President Bashar al-Assad.

The Swedish-Italian diplomat "hopes to set in motion as soon as possible" his project to halt fighting in Aleppo for six weeks, said a member of his delegation who declined to be identified.

De Mistura has met government officials and opposition chiefs in recent weeks to promote his plan for a temporary truce in Aleppo in order to move aid into the northern city.

Once Syria's commercial hub, Aleppo has been devastated by fighting that began in mid-2012, and the city is now split between loyalist forces and rebels.

De Mistura said last week that the government had shown a willingness to suspend aerial bombardment of Aleppo for six weeks to allow for a humanitarian ceasefire.

Under the plan, rebels would be asked to suspend rocket and mortar fire there during the freeze.

De Mistura incurred the wrath of the opposition earlier in February by describing Assad as "part of the solution" to Syria's conflict.

About 220,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests that spiralled into a multi-sided civil war drawing foreign jihadists.

Source: AFP