Senior Conservatives are calling for the government to scrap the legally enshrined rule forcing the UK to spend 0.7 per cent of national income on foreign aid, making more funds available to the military.

The 0.7 per cent pledge was made law by former Prime Minister David Cameron, but could be removed from the Tories’ next manifesto if critics have their way.

According to one proposal backed by the Defence Select Committee, reported by The Times, the policy could be replaced with a commitment to spending three per cent of national income on “security”, which would include the military as well as international aid.

Currently, the Minister of Defence has been guaranteed just two per cent of national income, the baseline amount required for NATO membership, and the proposed new system could make more available to them.

The definition of aid spending is contentious, and currently, the Organisation for Economic Co-operation and Development does not include security and peacekeeping operations in the category.

Britain would need to push for this to change to implement the new plan.

The military is currently facing a severe funding shortage at a time of increased global security threats. The high cost of Britain’s new aircraft carriers and the failure of the government to release sufficient funds to support the force means the size of the Royal Marines is due to be cut.

A government spokesman said talk of scrapping the current aid pledge is “pure speculation”, adding: “As a global, outward-looking country we take our international responsibilities seriously and remain fully committed to them.”

In December, Chancellor of the Exchequer Philip Hammond hinted the aid pledge could be scrapped at the next election, saying all protected areas of spending would be reviewed before the Conservative manifesto was produced ahead of the 2020 election.

The chancellor told the Treasury Select Committee: “Later on in the parliament, we will have a spending review. That is the right time to look in the round at all the commitments that have been made for this parliament.

“Tax, spending, ringfences. I think these things need to be looked at. We will have to have that debate and the right time… is the spending review.”