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David Cameron is depending on 70,000 “moderate” Syrian opposition fighters to topple Islamic State in Syria - but this is an army of 120 different rebel groups.

Far being a unified army with a common leader, the ragtag force Cameron is pinning his hopes on actually consists of fragile alliances with radically different aims.

Within this makeshift battalion composed of Kalashnikov-wielding warriors - most of whom have no military training - there is more opposition to President Bashar Assad than there is to IS.

Some factions are battling for freedom in a specific region of Syria, some want to oust other rebel groups, and some even support al-Qaeda.

(Image: Rex)

The Southern Front alone consists of 25,000 fighters in 58 factions while the Northern Free Syrian Army is a 20,000-strong force centred on 14 different units.

Those based around Aleppo in the north have little to do with those from Daraa in the south.

Equally, there are radical religious differences between the splintered rebel forces.

Read more:David Cameron's plan is based on fantasy

Many experts believe the Prime Minister’s vision of moderate rebels storming the IS stronghold Raqqa following a bombardment from Britain and its allies is naive.

Last night Ghadi Sary, a Syria specialist at the Chatham House thinktank, said: “It was oversimplified when it was said that 70,000 were waiting. It would have been better to say there are 70,000 opposed to Assad who are not radical. The idea that they would take Raqqa is overstretching it.”

(Image: Rex)

One major problem with the Government’s planned reliance on friendly Syrian rebels is that the overthrow of Assad is a bigger priority for most.

Their supporters would be unhappy if they suddenly redirected their guns on IS instead of Assad, the most despised figure for many Syrians.

poll loading What do you think of David Cameron's plan to work with 70,000 Syrian rebels 0+ VOTES SO FAR Sounds like a smashing plan to me I can see a few problems with 120 untrained armies with different agendas co-existing This shows David Cameron is a useless leader and his plan can't possibly work

Charles Lister, author of The Syrian Jihad: Al-Qaeda, the Islamic State and the Evolution of an Insurgency, said: “They will not suddenly overnight become British tools to fight Isil as long as they are still having to fight Assad.”

(Image: JOHN CANTLIE)

A more likely force to mount a full-scale assault on Raqqa is the Democratic Forces of Syria, a combination of Kurdish units and some Syrian Arab groups.

They, however, are thought to number less than 10,000.

The Kurdish groups involved in insurgencies against both IS and the Turkish army on the Syria-Turkey border are not included in the 70,000 for fear of offending Turkey, a key ally.