Russia has launched a “dirty tricks” campaign against Britain and the US in the wake of the Syria airstrikes as Boris Johnson warned of the need to be prepared for retaliatory attacks.

Whitehall sources on Sunday night confirmed a Pentagon analysis that showed a 20-fold increase in Russian-sourced “disinformation” being spread online since the cruise missile attacks on Syria in the early hours of Saturday.

There are fears that it could be a precursor to a campaign of cyber attacks by the Kremlin, and the Foreign Secretary said Britain must take “every possible precaution” to guard against it.

It comes as Jeremy Corbyn attempts to force a Commons vote on Syria that could make it harder for the Prime Minister to mobilise the Armed Forces without the permission of MPs.

Mr Corbyn will on Monday ask the Speaker to grant an emergency debate that is likely to lead to a vote which will scrutinise Mrs May’s judgement in authorising the airstrikes.