Activists say clashes have flared up between Syrian troops and rebels on the southern outskirts of Damascus as part of a weeks-long government push to advance on opposition-held areas.

The British-based Syrian Observatory for Human Rights says fighting is underway around the rebel-held Hejeira suburb on Tuesday.

The Observatory also says clashes are taking place near the government-controlled Sayyida Zainab neighborhood, known for a famous Shiite shrine.

The Observatory and a spokeswoman for a Damascus Syrian rebel council says Shiite fighters from the Lebanese militant group Hezbollah are fighting alongside Syrian government forces in the two neighborhoods. The spokeswoman spoke on condition of anonymity, fearing for her safety.

Government troops and pro-Assad fighters have seized four other nearby neighborhoods in recent weeks.