Rebels in Syria claim to have shot down an army fighter jet in the skies above the village of Al Muhassan.

An amateur video published on a social media website on Monday shows a plane engulfed in flames in the sky.

The content of the video cannot be independently verified, but if true, it is another example of the escalating violence in Syria.

The head of the United Nations monitors in the country has blamed both forces loyal to President Bashar al-Assand and rebel fighters for ignoring the plight of civilians as the fighting intensifies.

Activists claim more than 18,000 people, including soldiers, rebels and civilians have been killed since the start of the Syrian uprising against Assad in March last year.

Assad's forces are battling to regain control of the city of Aleppo.