The group said about 80 per cent of the shortfall could be attributed to Italy and France alone.
The report said: "Italy and France ... have made exceptionally poor progress and are damaging the G8's collective credibility.
"Given how far some G8 countries have drifted from their promises, it will be challenging for the group to get back on track to keep their commitments."
Many G8 countries have spent billions of dollars on fiscal stimulus packages to spur global economic recovery, which has impacted upon their ability to increase foreign assistance.
But African countries are being hit by the global economic slowdown too, and the financial crisis threatens to undo more than a decade of progress in reducing poverty and spurring high economic growth.
|Berlusconi, centre, and Sarkozy, right, have been criticised for reducing aid to Africa [AFP]
Finance ministers from the G8 are preparing to meet in Italy this weekend to discuss the state of the world economy.
France's development assistance to Africa took a dive from 2007 to 2008 and it has delivered only seven per cent of what it promised at Gleneagles.
Meanwhile, Italy has so far delivered only three per cent of what it promised and has cut aid to Africa since the 2005 summit.
Silvio Berlusconi, Italy's prime minister, has responded to the accusation, saying leaders in certain African countries had funnelled aid into their own bank accounts rather than use it to help their people.
He said donors had to make sure governments used the aid for schools, hospitals, roads and railroads, and not to enrich political elites.
"It's a big problem that requires a big decisive response from all those who are fortunate enough to be well-off," he said.
To get back on course, the G8 members will need to deliver on average an additional $7.2bn each year in 2009 and 2010, the report said.
On a country-by-country basis, Canada, the US and Japan have exceeded their Gleneagles commitments, the One campaign said.
In addition, the report said that while Germany and Britain are currently off track in meeting their aid goals, both are making progress to meet their commitments that were more ambitious than the United States, Canada or Japan.
The report also said that Germany became a bigger donor to Africa than France last year, which has traditionally played a major role in its former colonies mainly in West Africa.
When it comes to aid effectiveness, Britain ranked first followed by Canada, Japan, Germany, France, the US and then Italy, the report said.
It said when used effectively, aid to Africa had produced results including providing Aids anti-retroviral therapy to four million people.
Invested aid also dramatically reduced deaths from the mosquito-borne disease malaria, and helped put some 34 million children in primary school between 1999 and 2006.