Strikes in Syria kill 28 civilians

At least 28 civilians have been killed in the heavy bombardment of a besieged Syrian rebel stronghold east of Damascus, a monitoring group says.

According to the Syrian Observatory for Human Rights, rockets fired by regime forces on Sunday rained down on Douma, one of the largest towns in the opposition-held Eastern Ghouta region.

Observatory head Rami Abdel Rahman said air strikes also hit Douma and the nearby town of Saqba, but it was unclear whether they were carried out by Syrian or Russian warplanes.

The air strikes and rockets wounded dozens, he said.

"One of the air strikes on Douma hit near a school, killing the school's principal," Abdel Rahman told AFP.

Government forces regularly bombard Eastern Ghouta, and rebels there fire rockets and mortar shells into the capital.

On Sunday, a young girl was killed and three people were wounded in rebel mortar fire on Damascus, according to the national news agency SANA.

Last month, regime forces and rebel groups tried to reach a 15-day ceasefire in Eastern Ghouta, but the talks failed and violence has resumed.