Syria rebels
Prime Minister David Cameron claimed there are about 70,000 Syrian opposition fighters with whom the UK can coordinate attacks against Isis Getty

Prime Minister David Cameron was warned by military officials against announcing that 70,000 Syrian opposition fighters were prepared to help wipe out the Islamic State (Isis). The cautions were issued as fears mounted that the assertion could become Cameron's "dodgy dossier".

Whitehall and defence sources told the Times that such a precise number could come back to haunt the prime minister as politicians could mistakenly presume that British air strikes would immediately clear the path for anti-IS forces to reclaim Raqqa, the terrorist organisation's de facto capital. Cameron said: "We believe there are around 70,000 Syrian opposition fighters - principally the Free Syrian Army - who do not belong to extremist groups ... and with whom we can co-ordinate attacks on ISIL (IS)." He said that the figure had been provided by the UK's Joint Intelligence Committee.

It is understood that the military officials are not concerned about the figure itself, but by the use of a precise figure. The fears were fuelled by former Labour prime minister Tony Blair's previous assertion that Saddam Hussein had the capacity to deploy weapons of mass destruction within 45 minutes, a claim which turned out to be false.

"There were Ministry of Defence officials who maybe felt scarred after the previous dossier," a Whitehall source told the Times. "They looked at the latest text and said that [the 70,000 figure] could become the '45 minutes' moment of this document." The source continued: "The concern was ...[that the 70,000 figure] will become the one thing that everyone latches on to, like the 45 minutes claim."

A defence source said: "There is a concern that it is a hostage to fortune, just like that 45 minutes claim from the dodgy dossier". He added: "That is just too recent in people's memories."

The number was met with deep scepticism and when Cameron was pushed to clarify it in the House of Commons on 2 December, he said: "I am not arguing that all of these 70,000 are somehow ideal partners." He added: "Do we wait for perfection?"

A Downing Street spokeswoman said that Ministry of Defence (MoD) officials did not raise concerns over the disclosure of the figure. Air strikes against IS were launched just hours after MPs voted to bomb the terror organisation.

Speaking on Question Time on 3 December, Green Party MP Caroline Lucas said: "Time and again in the House of Commons yesterday, the prime minister was challenged about where were these mythical 70,000 forces. They've become the bogus battalions, as the chair of the Defence Select Committee called them - the equivalent of the dodgy dossier because in a sense, they are just in David Cameron's head.

"Even if they existed, the idea that they are going to be willing to give up fighting Assad - which is what their primary focus is - to helping us with fighting Isil or Daesh I think is again, completely unsubstantiated."

When David Dimbleby canvassed public opinion on Question Time, one audience member said that air strikes in Syria were part of a racist backlash after the Paris attacks. "When Cameron stood at the despatch box he said that we had low collateral missiles. In reality that means we hope not to kill that many civilians. Why are people in Syria collateral damage and people in Paris victims? It's racist," he said to loud applause from the floor.