Syrian warplanes have bombed the suburbs of Damascus, while rebels have fired mortar shells at the capital on the first day of a major Muslim holiday, an activist group said on Tuesday.

Al Jazeera has also received reports of a bombing inside a mosque in the al-Tadmon neighbourhood, south of the capital Damascus, on the morning of the Eid al-Adha holiday.

The UK-based Syrian Observatory for Human Rights said rebels fired rockets and mortar rounds at three Damascus neighbourhoods. An amateur video posted online shows three rockets being fired, leaving a trail of dark smoke.

The Observatory says the regime bombed the Eastern Ghouta district of Damascus and rebel areas near of Hama, killing three children.

State television broadcast images of President Bashar al-Assad entering the Hassiba mosque in Damascus and waving to supporters before taking part in prayers.

The prayers were led by Imam Mohamed Tawfik al-Bouti, the son of Mohamed al-Bouti, a senior pro-regime religious figure who was killed in a bombing at a mosque in March.

Tuesday's fighting shows how entrenched both sides in Syria's civil war have become. Earlier in the fighting, the sides occasionally attempted to observe holiday cease-fires.

More than 115,000 people have been killed in Syria since the beginning of the conflict in March 2011, according to the Observatory.

Source: Al Jazeera and agencies