Britain’s most dangerous extremists will be forced to undergo a mandatory “deradicalisation” programme, in a major overhaul of the Government’s counter-terror strategy.

The “intensive” scheme could be used to target jihadists who have returned to Britain from Syria with psychological help, or to change the minds of radicals who support terrorist ideologies in the UK.

Where it is legally possible, the Government will make it mandatory for individuals to attend these sessions, under the plan.

It forms part of the Government’s anti-terrorism strategy, which is being reviewed in light of the wave of attacks in Europe, to strengthen security at airports, on trains and at major public events.

The strategy is likely to include dramatically increasing the number of spies to uncover terrorist plots, more armed police to stop jihadist gun attackers, a new scheme to protect Britain against a “mass impact biological attack” and tougher measures to stop terrorists getting hold of explosives from commercial and military stocks.