Syrian rebels have launched a major assault on a northern airbase used to deploy regime air power, on the eve of a crucial meeting to decide the future of the opposition.

The attack on the Taftanaz base, from where helicopter gunships raid opposition positions and rebel-held areas, comes after troops launched an unprecedented wave of air strikes this week in a bid to reverse rebel gains.

Heavy Fighting

A video posted on the Internet says eight battalions were taking part in the attack, including the radical Islamist Al-Nusra Front, and shows a missile launcher mounted on the back of a pick-up truck firing on regime positions.

The Syrian Observatory for Human Rights, confirmed that "heavy fighting" broke out near the base in Idlib province, where rebels have seized new ground this week.