At least 11 civilians were killed during Syrian regime's attacks on a suburb of Damascus' Eastern Ghouta on Sunday, according to a pro-opposition civil defense official.

Speaking to Anadolu Agency, Mahmud Adham said regime forces shelled the towns of Hamouriyah, Sabqa and Kafra Batna in East Ghouta, killing 11 people, including an activist. Adham also said two students were injured by mortar shelling at a school in Kafra Batna.

Yusuf al-Bustani, a member of Local Coordination Comities in Eastern Ghouta, said the regime attacks targeted the towns of Sabqa, Hamouriyah and Kafra Batna in Eastern Ghouta.

"Regime forces attempted to sneak into Ain Tarma and Jobar suburbs in Damascus but opposition group repelled the attempts," al-Bustani said.

Al-Bustan warned that a humanitarian catastrophe was unfolding in the regime-blockaded Eastern Ghouta.

"The regime uses starvation as a weapon against civilians as it had done in al-Yarmouk refugee camp, Madaya and al-Zabadani," he said.

The four-year siege on east Ghouta has led to the deaths of more than 400 civilians, including 206 children and 67 women, due to a lack of food and medical supplies, Anadolu Agency (AA) reported. Since the Syrian civil war began in 2011, sieges and starvation have been used as tools of war. Placing cities under siege and cutting off access to roads, food and medical supplies have left humanitarian aid providers unable to reach the trapped populations of civilians not allowed to leave the cities.