DAMASCUS, March 21 (Xinhua) -- The death toll rose to 43 in a rebel rocket attack on a crowded marketplace east of the Syrian capital Damascus, a monitor group reported on Wednesday.

The improvised rocket hit the Kashkoul marketplace east of Damascus on Tuesday evening, leaving destruction and carnage scenes.

The Syrian Observatory for Human Rights said the death toll could rise as 35 people were wounded, some critically.

The attack is one of the deadliest caused by rebels' rocket fire in Damascus.

This comes as the Syrian army is advancing in the depth of the rebel bastions in Eastern Ghouta in the countryside of Damascus.

The state TV said the Syrian forces reached on Tuesday the farmlands of the Ayn Tarma area, a key bastion of the Failaq al-Rahman rebels, who are responsible for most of the mortar and rocket attacks on the capital.

The Syrian army has already controlled over 80 percent of Eastern Ghouta, the last remaining threat to the capital.