The Prime Minister insisted he was “proud” that the UK would not “balance its books on the back of the poorest”, and warned that failing to support countries at the forefront of the Arab Spring would give “oxygen” to extremists.
Speaking at the end of the G8 summit in France, Mr Cameron also made clear his frustration that other wealthy nations were not fulfilling pledges on aid.
“Britain will keep its promises and I was tough in urging my counterparts to do the same,” he said. “The reality is that as a whole the G8 has not.”
He added: “Of course it is a tough argument to make when we are making tough choices at home, but I think it’s the right thing.”
Mr Cameron said he remembered watching Band Aid and Live Aid on television, and the impact those events had.
Referring to the G8 pledge of spending 0.7 per cent of GDP on aid by 2015, Mr Cameron said: “These things matter and if we are going to try to get across to the poorest people in the world that we care... then we have got to keep our promises.”
Mr Cameron said: “The big test for the G8 was whether we could respond to the momentous events that we have seen in North Africa and the Middle East. I would argue that we have responded.”
He went on: “There are those that argue that these North African countries, they are not the poorest in the world, and we should concentrate either on our own affairs, or indeed elsewhere.
“I reject that approach. We should be in no doubt that if we get this wrong, if we fail to support these countries, we risk giving oxygen to the extremists who prey on the frustrations and aspirations of young people.
“You would see, I believe, if we fail, more terrorism, more immigration and more instability coming from Europe’s southern border.”
The two-day summit in Deauville, France, was dominated by the response to the Arab Spring and the situation in Libya.
Mr Cameron has announced that the UK is allocating £110m over four years to strengthen justice systems, cut corruption, encourage political parties, and broaden economic opportunities.
Aides claimed that, relative to the UK’s economy, the commitment was in line with a one billion-dollar debt relief package unveiled by America.
After the prime ministers of Egypt and Tunisia briefed G8 leaders, the final declaration from the summit included a suggestion that multilateral development banks could provide the nations with more than $20 billion over the next two years.
G8 countries “are already in a position to mobilise substantial bilateral support to scale-up this effort”, it said.
The declaration claimed the nations were “strongly committed” to meeting pledges on aid levels, and being “transparent” about how much they were giving.
But Mr Cameron is said to have pointed out in a private session earlier that the UK was the only country firmly on track to meet a target for giving 0.7 per cent of GDP by 2015.
Mr Cameron said he knew the argument over aid was “controversial”, but insisted it could be won.
“If you are not convinced that it is right to vaccinate children against diarrhoea, to try to stop preventable diseases, to try to save mothers in childbirth – if that doesn’t do it for you, what about this argument?
“That these countries that are broken, like Somalia, like Afghanistan, if we don’t invest with them before they get broken, then we end up with the problems.”