David Cameron G7
David Cameron holds a news conference during the G7 summit in Germany in 2015 Christian Hartmann/Reuters

Britain is the only G7 nation to spend 0.7% of its GDP on foreign aid, a report has found. The UK's aid budget soared from £5.9bn ($8.6bn) in 2004 to £13.2bn in 2014 – an increase of 144% across a ten year period.

The findings show that Britain now contributes towards a fifth of the entire aid budget of the G7. Aside from Britain, leading global economies in the club include Canada, Germany, France, Italy, Japan and the US.

The 0.7% commitment was established by the UN in 1970 and last year, the UK enshrined it in law. Britain first met the target in 2014 and with a population of 65m people, £188 per person was spent the following year. The US gave £61 per person from a population of 332m.

Shipley MP Philip Davies blasted the spending as "unjustifiable" at a time of austerity and said: "We are clearly the mugs of the world. The Prime Minister might think it makes us look compassionate to spend more and more money when we're in debt – to hand it over to some fantastically corrupt countries around the world. I personally think it makes us look stupid.

"You should spend what you can afford. It is absolutely unjustifiable," he added.

The G7 gave Britain five "cherry blossom" badges for its commitment to overseas aid while other countries managed just three. Figures show that Germany and France give around 0.4% of GDP, Canada contributes less than 0.3% and the US, Japan and Italy all give less than 0.2%.

"G7 countries have made some progress on their respective commitments to increase their development assistance," the report said.

"The results however remained mixed and several of the commitments made at the Gleneagles summit in 2005 [hosted by Tony Blair] have yet to be fulfilled. With the exception of the UK, G7 members faced challenges in meeting their commitments that related to the 0.7% target," it added.

Tory backbenchers accused the government of not putting its people first. Wellingborough MP Peter Bone said: "We should learn a lesson from other countries that put their populations first and decide to spend money at home, rather than to give away a sum of money which is completely not based on need – it's based on a percentage."

Aldershot MP Sir Gerald Howarth blasted the "fleecing" of UK taxpayers "in order to give the money to foreign governments." He said: "Foreign aid has a role to play, but certainly not on this level.

David Cameron will be in Japan for the G7 summit where the global economy, terrorism and threats to the steel industry are on the agenda. Although it is not officially on the summit's programme, Cameron will also be hoping to win support for Britain's continued membership of the EU ahead of the referendum on 23 June.