The ongoing Syrian conflict is further muddling into a deeper crisis as two main anti-Assad groups are set to confront each other.

The "Islamic State in Iraq and Greater Syria", better known as the al-Qaida wing in the region, has threatened to launch attacks on the Free Syrian Army (FSA), the umbrella group also fighting against president Bashar al-Assad's regime.

Although the differences between the two groups became palpable recently, this is the first open confrontation between the two anti-Assad outfits.

The Islamist al-Qaida organisation has posted a message on an extremist website signifying an attack on the "moderate" FSA in Syria's second city of Aleppo.

The statement entitled Fighting Evil said hereafter the campaign will be aimed against Syrian regime and the FSA fighters who target "Islamic State activists".

The Al-Qaida-affiliated Islamic State of Iraq (ISI) had officially joined forces with Jabhat al-Nusra in April 2013, calling their union an "Islamic State in Iraq and Greater Syria".

Following the uprising, which began in March 2011, the crisis in Syria gradually turned into a sectarian conflict. The recent spate of sectarian violence has seen the Sunni-led opposition vowing to uproot Assad, who belongs to the Alawite minority of Syria.

The sectarian violence in Syria has also frequently fuelled skirmishes in neighbouring countries including Iraq.