Cairo: At least 12 people were killed Tuesday and several others were wounded in air raids by forces loyal to President Bashar al-Assad in the northwestern Syrian province of Al-Raqqa, the Syrian Observatory for Human Rights (SOHR) reported.

The air strikes targeted a building in the Al-Thakna district near an Islamic State (IS) stronghold in western Al-Raqqa; along with the governorate building in the south of the province, and a mosque in the Al-Busarya neighbourhood.

SOHR said it expects the death toll to increase as many of the wounded were in serious condition.

The London-based NGO announced last week that the Syrian army has increased the number of air strikes and launched a total of 2,973 bombing raids in various provinces over the last few months causing at least 735 deaths.

More than 200,000 people have died since the conflict in Syria broke out in March 2011, according to the United Nations.