Syrian rebel fighters have been pictured eagerly unpacking Chinese-made surface-to-air missile launchers understood to have been smuggled into the country by African arms dealers.

Taken in a remote area north of the city of Aleppo, the photographs show fighters from the Free Syrian Army assembling FN-6 anti-aircraft missile launchers for use against soldiers loyal to the Assad regime.

The Chinese-made weapons are thought to have been provided to the Free Syrian Army by sympathisers in Qatar, who are likely to have purchased them from dealers with links to corrupt officials in the Sudanese government, before having them smuggled into Syria through Turkey.

Weapons: Fighters from the Free Syrian Army eagerly assemble an FN-6 anti-aircraft missile launcher for use against soldiers loyal to the Assad regime

Power: The Chinese-made weapons are thought to have been provided to the FSA by sympathisers in Qatar

The exact source of this particular batch of Chinese-made weapons is not immediately clear, although only a handful of nations possess the FN-6 - most of them in Asia.

Sudan is known to have purchased a large number of FN-6s from China and - despite international arms embargoes and the government's strong relations with Assad's allies in Iran - many of them appear to have ended up the hands of the Free Syrian Army.

Last year the New York Times tracked a Sudanese shipment of Chinese-made anti-aircraft missiles and newly manufactured small-arms cartridges to rebel fighters in Syria.

The weapons are likely to have been sold directly to Sudan by weapons manufacturers in China. FN-6 missiles were displayed at Sudan's Independence Day military parade of 2007.

Once in Sudan, the weapons can fall into the hands of either corrupt officials or local warlords, who offer them for sale on the international black market, where wealthy Qataris, Jordanians and Saudis who oppose Assad's regime can purchase them and have them shipped directly to rebel groups.

Unboxing: The exact source of this particular batch of Chinese-made weapons is not immediately clear, although only a handful of nations possess the FN-6 - most of them in Asia

Arms: Free Syrian Army sympathisers in Qatar are likely to have purchased the weapons from dealers with links to corrupt officials in the Sudanese government, before having them smuggled into Syria through Turkey

It is highly unlikely the Free Syrian Army would have purchased the surface-to-air missile launchers directly from China, who along with Iran and Russia maintain good relations with the Assad regime.

Nor is it feasible that the rebels acquired the weapons in their usual method - from regime soldiers that have either abandoned their posts or defected to the FSA.

The Syrian regime has no record of using the FN-6, although it does hold approximately 4,235 surface to air missile launchers from different manufacturers.

Specially designed to engage low flying targets, the FN-6 is considered China's most sophisticated surface to air missile launcher to date.