At least 15 people were killed Thursday and some 100 others were wounded in rocket attacks by rebel militias and airstrikes by forces loyal to President Bashar al-Assad on Damascus and its suburbs, official media and activists reported.

The Syrian Observatory for Human Rights (SOHR) said at least four people were killed, including a policeman, when the insurgent Jaysh al-Islam (Army of Islam) militia fired 63 rockets from Eastern Guta, the main opposition stronghold on the outskirts of the capital.

Citing a police source, the official Syrian news agency SANA said the attacks resulted in the deaths of three people and wounded 30 others, blaming "radical terrorists" for the attacks, which also caused damage to houses and vehicles.

On the other hand, regime forces doubled the air raids they have been carrying out in the cities of Duma, Arbin, and Eastern Guta, leaving at least 12 people dead, including a child, and wounding 100 others.

The leader of Jaysh al-Islam, Zahran Alush, issued a statement two days ago in which he declared the Syrian capital a "military zone".

He explained that he took this decision to counter the bombings carried out by the regime forces in Duma and other towns in Eastern Guta, and in light of the concentration of barracks, security centres, rocket bases and police checkpoints in Damascus.

Alush urged civilians, members of diplomatic mission and students not to approach any military barracks or checkpoints starting from Wednesday morning, and until further notice.

More than 200,000 people have died since the Syrian civil war began in March 2011, according to figures verified by the UN.