Prime Minister David Cameron proclaimed yesterday that Britain's military is a "first-class player" after criticisms from a former US defence secretary - but immediately faced tough questions over his priorities from campaigners.

Robert Gates said an erosion of Britain's defence forces had reduced its ability to be a "full partner" to the United States across the whole range of military operations.

But Mr Cameron insisted the Ministry of Defence budget remained the fourth largest globally and promised more investment was being made to enhance its future capabilities.