Anti-government forces in Syria have reportedly stepped up their offensive in the central part of the country, while taking control of much of Aleppo in the north.

The Syrian Observatory for Human Rights said some rebel forces have been carrying out a major attack on Aleppo since Wednesday, and have taken control of an airport.

The group said the forces also seized several cities and towns in the central Hama province, which is a transportation hub connecting to the capital Damascus.

Syrian President Bashar al-Assad reportedly spoke over the phone with United Arab Emirates President Sheikh Mohamed bin Zayed Al Nahyan on Saturday.

Assad was said to have told him that Syria can defeat all terrorists and their supporters, an apparent hint that his country could launch a counterattack.

Russia, which supports the Assad administration, reportedly carried out air strikes on targets including the anti-government forces' strongholds.

The Syrian Observatory for Human Rights said more than 320 people, including civilians, have been killed in Aleppo and elsewhere in Syria in the latest round of attacks.

The Associated Press published images of a camp hosting displaced people in a province adjacent to Aleppo.

The footage taken on Saturday shows workers preparing mattresses and relief supplies while children and elderly people huddle together.

Concerns are mounting over the worsening humanitarian situation in Syria, including the increasing number of displaced people and the recent escalation of fighting.