BEIRUT (Reuters) - Air strikes killed 23 people in Syria’s rebel-held eastern Ghouta district, just outside Damascus, a war monitor reported, and a woman was killed by shelling inside the government-held capital on Monday, state media said.

Warplanes struck the towns of Zamalka, Arbaeen, Hazza and Beitu Soua, said the Britain-based Syrian Observatory for Human Rights.

The Syrian army of President Bashar al-Assad, backed by Russian air power and Shi’ite Muslim militias, has besieged eastern Ghouta, the largest remaining rebel bastion near Damascus, for years.

Shelling of the Old City of Damascus, which is held by the government and lies near the rebel enclave that includes eastern Ghouta, killed a woman and injured three other civilians, state news agency SANA reported.

International concern has been growing over the fate of eastern Ghouta as bombardment by the Syrian military and Russia has increased in recent months and as shortages of food and medicine have led to severe malnutrition.

Assad and his allies have gained momentum in the seven-year-old war, gaining territory, pushing rebels from most big cities, and forcing several pockets to surrender last year.