The head of the Army has said Britain should “train and equip” a “citizen army” to ready the country for a potential land war.

But General Sir Patrick Sanders, the outgoing Chief of the General Staff (CGS), said even that would be “not enough” as he pointed to allies in eastern and northern Europe “laying the foundations for national mobilisation”.

In a speech on Wednesday, the military top brass said increasing Army numbers in preparation for a potential conflict would need to be a “whole-of-nation undertaking”.

The comments, first reported by the Daily Telegraph, are being read as a warning that British men and women should be ready for a call-up to the armed forces if Nato goes to war with Russia.