BEIRUT — Syrian troops captured a major rebel stronghold east of the capital Damascus on Saturday and took large parts of another, squeezing insurgents and forcing thousands to flee to regions controlled by the government.

The Britain-based Syrian Observatory for Human Rights and Oways al-Shami of the Syrian Civil Defense said troops have taken Kafr Batna and large parts of nearby Saqba.

The capture of those sectors is another blow to opposition fighters who have lost more than 70 percent of the area known as eastern Ghouta since President Bashar Assad’s forces began a crushing offensive under the cover of airstrikes on Feb. 18. The violence has left nearly 1,400 people dead, more than 5,000 wounded and forced tens of thousands to seek shelter in areas under government control.

The intensity of the shelling and airstrikes has made it almost impossible for ambulances to move and wounded people cannot reach clinics, said Hamza Hassan, a surgeon working at one of the hospitals in eastern Ghouta.

Syrian state news agency SANA said the army stepped up military operations in eastern Ghouta and inflicted “heavy losses on terrorist groups in personnel and military hardware.” It said troops reached the center of Kafr Batna and Saqba.

Rebels still control the towns of Arbeen, Zamalka, Ein Tarma and Jobar on the southern edge of eastern Ghouta. Eastern Ghouta has been split into three parts – the largest rebel-held town of Douma to the north has been cut off from nearby Harasta, and both have been split off from the rest of the area.

The Observatory said 30 people were killed in a Saturday morning airstrike on Zamalka that hit a group of people trying to flee into government-controlled areas.

The opposition’s Syrian Civil Defense said the airstrike killed dozens and wounded scores, adding that paramedics are trying to help survivors.