The Syrian prime minister has said the country's military and the Russian air force are preparing a joint operation to take the city of Aleppo from rebels.

This is on the back of a report from the Syrian Observatory for Human Rights that at least 16 pro-government fighters, and 19 members of Al-Nusra and allied rebel groups were killed in the city.

The clashes comes as a ceasefire brokered by the United States and Russia continues to largely hold across Syria. However,Syrian Information Minister Omran al-Zoubi said the conditions of the truce do not apply to the fight against terrorist groups in the country.

In areas where the Al-Qaeda linked Al-Nusra group is fighting alongside allied rebel groups, violence has been frequent throughout the ceasefire.