A pro-government Syrian TV said 15 people were massacred by "armed terrorist groups" in central Syrian towns on Sunday, while activists reported violent clashes between the Syrian troops and armed rebels in the northern province of Aleppo.

The Sama TV reported the massacre in the towns of al-Haidarieh and Ghasanieh near the central province of Homs, placing the initial toll at 15.

On the same incident, the pan-Arab al-Mayadeen TV said hundreds of armed insurgents stormed the two towns overnight and rousted locals out of their homes before killing 17 of them and kidnapping seven others.

Al-Mayadeen gave no further details, but also reported a big blast targeting a command center of the rebel Free Syrian Army in Hass area near the northwestern province of Idlib and killing four of its leaders.

In separate accounts Sunday, the opposition Local Coordination Committees (LCC) said intense clashes are taking place in the northern Aleppo city between the government troops and armed rebels.

The clashes are taking place at the neighborhoods of Salahuddien, al-Azamieh and Saif al-Dawla in Aleppo, the activists said.

The pro-government Sham FM said scores of armed insurgents were killed Sunday at Dar-Azzah and al-Jandoul roundabout in Aleppo, a city of about 3 million, which has emerged as a key battleground in Syria's conflicts.

In the capital Damascus, the LCC said the Syrian troops stormed Sunday the restive suburb of Harasta, carrying out house-to-house raids and arrests.

The LCC also reported violence throughout the country including clashes between troops and rebels, who are trying to turn the tide in the 18-months-old crisis in Syria.

The activists' claims could not be checked independently, but clashes in the suburbs of Damascus have become increasingly common despite the lull every now and then in those areas.