Syria's president Bashar al-Assad
Syria\'s president Bashar al-Assad gestures during an interview - (SANA/Reuters)

Amid the looming US strike, Syrian President Bashar al-Assad has warned that the military intervention will spark a widespread conflict in the region plunging the Middle East into a deeper crisis.

In an interview to the French daily Le Figaro, Assad once again firmly denied his forces had used chemical weapons against the civilian population, a charge which forced the US to consider a military strike on Syria.

"The Middle East is a powder keg, and the fire is approaching today. Must not only talk about the Syrian response, but what might happen after the first strike. But nobody knows what will happen. Everyone will lose control of the situation when the powder keg explodes. Chaos and extremism will spread. The risk of a regional war is there," said the embattled Syrian leader, according to excerpts of the interview.

The fallout of an intensifying conflict in Syria has already been felt in all of its neighbouring countries during the two and half year long crisis. The uprising-turned-civil war has fuelled Shiite-Sunni clashes in Iraq, sparked tensions in Turkey and increased confrontation with Israel.

The clashes have also dragged the Lebanon-based Hezbollah into the conflict allowing militant groups to exploit the volatile situation. There were reports earlier that the Syrian crisis is increasingly becoming a breeding ground for terrorist outfits like al-Qaida.

Alongside the warning, Assad demanded that the US and France furnish tangible evidence for the alleged gas attack, which is said to have claimed nearly 1,400 lives including those of women and children.

Assad said: "Those who make accusations must show evidence. We challenge the United States and France to do this. [US President Barack] Obama and [French President Francois] Hollande have been incapable of doing this, including for their own people."

Assad's remarks came hours before French authorities declassified an intelligence document which reveals the extent of the use of chemical weapons in Syria.

The document, which was given to French lawmakers, says pro-Assad groups had used the deadly weapons at least three times since April including the 21 August attack.

The French report said "massive use of chemical agents" was involved and pointed fingers at the Assad regime for the attacks.