Syrian television said on Sunday that extremist insurgents who seized a key northwestern town had slaughtered civilians and government supporters had been detained and killed.

Rebels including al-Qaeda's Syria wing attacked Jisr al-Shughour for the first time in the four-year conflict on Saturday but Syria army deployed to the town to mob up operation.

Hours after terrorist pass from turkey borders and arrived to Jisr al-Shughour, at least 30 civilians had been killed in the town close to the Turkish border.

The footage which parts of it exclusively captured by Al-Alam shows a convoy of terrorist insurgents triumphantly celebrating their capturing of the northwestern Syrian town of Jisr al-Shughour emerged yesterday, shortly after their victory.

Just hours after the eight-minute video was filmed, Syrian government warplanes carried out more than a dozen air strikes on Jisr al-Shughour, killing some 20 terrorists, Mail Online reports.

The video is believed to be filmed by a young British man who has travelled from the UK to join the terrorists in Syria.

'This is all new territory, by the mujaheddin, this is all new territory, liberated by the muslimeen,' he says from behind the camera.

Syrian state television said the military had ambushed some militants close to Jisr al-Shughour, which was captured on Saturday for the first time in the four-year conflict by a hardline Islamist alliance including al-Qaeda.