The UK government had prepared a secret plan to train and equip tens of thousands of rebels to fight against Syrian president Bashar al-Assad, but the move was aborted, BBC reported.
The idea was mooted by Lord David Richards, who was then the chief of defence staff, and actively considered by David Cameron and the National Security Council.
The BBC said in its Newsnight programme, the initiative to train up to 100,000 anti-Assad forces, was considered two years ago, but had to be ultimately shelved as it was thought to involve too much risk.
The Cameron administration had been warned by Lord Richards that there were only two ways of resolving the Syrian conflict - either defeating Assad or letting him win.
The plan envisaged, provision of air cover by western powers and Gulf allies to allow the rebel army to press ahead against Assad in a "shock and awe" strategy similar to that of Iraq in 2003.
Top US officials, including general Martin Dempsey, the highest military officer in Washington had also been consulted on the matter.
There has been intense turmoil in Syria in the last three years, with anti-regime groups fighting to oust Assad but with little success.
Syria has seen intense turmoil over the past three years as the anti-regime groups are relentlessly fighting to uproot Assad, but with little success.