Britain is to supply rebels in Syria with defences against chemical attacks, including protective hoods, after repeated claims that regime forces have been using sarin gas.

The move comes as President Bashar al-Assad’s forces have made significant recent gains in the vicious civil war and the Cameron Government remains undecided about whether to arm to the opposition fighters after warnings from senior military officers that simply sending limited numbers of weapons would have little effect on the ground.

William Hague, the Foreign Secretary, said he was sending the WMD-related equipment, worth £656,800, as a “gift” as it was “a matter of special urgency”. He has had to follow this path after the Commons passed a motion last week calling on the Government to seek the “explicit” consent of Parliament to send arms to the rebels.

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The Assad regime has denied deploying chemical weapons and has accused the rebels of doing so. Britain and France have presented “evidence” to the UN that sarin had been used.