L'AQUILA, Italy - Prime Minister Stephen Harper held up Canada as a model of accountability and restraint Friday at the close of a G8 summit -- then had to issue an apology for falsely slagging a domestic political opponent on the international stage.

Harper closed out the three-day Group of Eight meetings with a ringing demand for the world's major industrialized countries to make realistic promises and then fulfil them.

"It's not just a moral question," Harper said after referencing issues from climate change to African aid.

"When we as the G8 make commitments and we don't fulfil them, this undercuts the credibility of our process. And that is a serious problem."

As host of next year's summit in Huntsville, Ont., Harper said Canada wants to see accountability near the top of the agenda.

His message of rectitude was undermined, however, by a nasty, personal tirade in both official languages against Michael Ignatieff.

Harper teed off on the Liberal leader for allegedly suggesting Canada could be excluded from some future international summitry.

"Mr. Ignatieff is supposed to be a Canadian," chided Harper, a message perfectly in tune with current Conservative attack ads that question Ignatieff's links to Canada.

Harper and an aide both later apologized because the comments in question were not Ignatieff's.

The prime minister's errant detour into domestic mudslinging took the shine off what was otherwise a good day for the Canadian government.

International aid groups offered relative praise to Canada for actually meeting previously set G8 targets on increasing aid to Africa.

"Canada's doubled its aid, but it needs to set a new, more ambitious target into the future," said Robert Fox, executive director of Oxfam Canada.

"For the other countries, quite frankly, their performance varies from poor to -- in the case of France and Italy -- borders on the criminal."

"Africa has got short shrift at this G8 and so there's a real expectation that next year in Muskoka they will deliver," added Fox.

The prime minister made a clarion call for help for the world's poorest, but made no promises for the 2010 agenda. He did, however, repeatedly sound a note of determined realism.

"Every year I've come to the G8 -- actually far less so this year -- but in the past every year we came here and we were under pressure to make more commitments," said Harper, who was attending his fourth such summit.

"This is how some countries . . . try and cover the fact the they haven't fulfilled their commitments, by making a bigger commitment."

He said Canada has a reputation for making modest promises and then keeping them -- although Harper couldn't resist pointing out the notable exception of Canada's Liberal-based Kyoto targets on reducing greenhouse-gas emissions.

As for African aid, Harper bluntly responded that he heard no convincing reason from other leaders why they haven't fulfilled the promises they made four years ago at the G8 summit in Scotland.

"I haven't heard any explanation on that. I'm not trying to single out countries here, but we've been very clear that, if anything, we will be taking the accountability theme . . . in terms of G8 commitments to the next step next year."

The G8 leaders formally announced Friday they will contribute some US$20 billion to food security -- essentially helping small-scale farmers -- over the next three years.

"There is an urgent need for decisive action to free humankind from hunger and poverty," said the G8 statement. "We will aim at substantially increasing aid to agriculture and food security."

Improving the productivity of small, local farms marks a significant change in the way international aid is delivered, and the move is being welcomed in many quarters.

"It's a total shift, a welcome and encouraging one," said Jacques Diouf, the chief of the UN Food and Agriculture Organization.

Dennis Howlett of the umbrella group Make Poverty History, called it "one of the very few new initiatives coming out of this G8."

But the UN's Food and Agriculture Organization last year said about $30 billion was needed for food security.

"A lot of this is not new money," Howlett noted.

"In Canada's case, it's money already in the aid budget -- but more is being put into agricultural development."

International aid groups implored Harper to make Africa a top G8 priority next year in Canada.

The multitude of participating nations at the L'Aquila summit and the range of issues left some observers wondering if the G8 format has become unwieldy.

Harper defended the annual summit but hinted at changes.

"Obviously we have to develop a wider body that will be more representative," the prime minister said of Italy's huge summit cast.

He then sounded a note of skepticism.

"I counted. At one point we had a G8, we had a G9, we had a G14 or 15, we had a G18, at one point a G19, another point a G25 and we finally ended with a G28."

Harper also noted there are parallel G20 meetings -- "which is now up to G24, last time I counted."

"So I think our challenge for the year ahead will be to try to use our presidency of the G8 to bring some coherence to this as we move forward."