DAMASCUS, March 14 (Xinhua) -- An array of rebel groups on Wednesday unleashed a wide-scale offensive in the countryside of Hama province in central Syria as part of retaliation against the Syrian military operations in the capital Damascus' Eastern Ghouta countryside, a monitor group reported.

The rebels' assault, dubbed "The Rage for Ghouta," is taking place in the northern and northwestern countryside of Hama, said the Syrian Observatory for Human Rights.

The rebels aim to advance and capture areas controlled by the Syrian army, starting their offensive on Wednesday morning with heavy shelling and rocket attack on the Syrian army's positions in Hama countryside.

The rebels succeeded to capture the northern neighbourhood of Kernaz area and most of the Hamamyiat area in the northern countryside of Hama.

The battles are coupled with Syrian airstrikes on the positions of the rebels in Hama countryside, said the Observatory, adding that 20 soldiers and rebel groups have been killed in the battles since Wednesday morning.

In the capital Damascus, the Syrian army continued its military offensive against the rebels in Eastern Ghouta, capturing new areas on Wednesday while securing the evacuation of civilians from areas in Eastern Ghouta.

The situation in Eastern Ghouta has flared up since late February following a wide-scale military operation by the Syrian army to dislodge al-Qaida-linked groups from the area.

On Sunday, the Syrian army split Eastern Ghouta into three parts, by tightening the siege on Douma in the north, the city of Harasta in the west and other towns and villages south of the region.

Eastern Ghouta, a 105-square-km agricultural region consisting of several towns and farmlands, constitutes the last threat to Damascus given its proximity to government-controlled neighbourhoods east of the capital and continuing mortar attacks on residential areas there.

Four major rebel groups are currently positioned inside Eastern Ghouta, namely the Islam Army, Failaq al-Rahman, Ahrar al-Sham, and the Levant Liberation Committee, known as the al-Qaida-linked Nusra Front.

The UN humanitarian agencies have sounded the alarm about the worsening humanitarian situation for 400,000 people in Eastern Ghouta, where activists said around 1,000 have been killed since a military showdown between rebels and the government late February.