A senior UN official has arrived in the Syrian capital to try and broker a freeze in fighting in the city of Aleppo.

The ceasefire would allow crucial humanitarian aid to be delivered to the city's beleagured residents as the UN tries to end the country's devastating civil war.

But the call is being viewed with scepticism by rebel groups who fear it will allow President Bashar al-Assad's forces to be deployed elsewhere.

Al Jazeera's Zeina Khodr reports from Beirut.