The sound of gunfire from a mosque in Damascus.

Amateur video out of Syria which could not be independently verified by Reuters appears to show heavy shelling in the capital.

Rebels say they have killed 70 security forces and pro-government militiamen over the past 24 hours.

Residents say security forces backed by helicopter gunships and artillery have been battling rebels in the heaviest fighting inside the capital since the uprising began last March.

Syrian security forces say they have confronted fighters who infiltrated the capital and have forced many of them to flee.

The fighting is expected to continue with neither side able to deliver a decisive blow.

Deborah Lutterbeck, Reuters