The number of poor people in developing countries dropped to record low levels between 2005 and 2008, the World Bank said in a report out Wednesday.
"This across-the-board reduction... marks a first since the bank began monitoring extreme poverty," the global institution said.
The study, based on some 850 household surveys in nearly 130 countries, defines "poor" as living with less than $1.25 a day.
Some 1.29 billion people, or 22 percent of the developing world's population, were poor in 2008, down from 1.94 billion people in 1981, the Bank said.
"The developing world as a whole has made considerable progress in fighting extreme poverty, but the 663 million people who moved above the poverty lines ... are still poor by the standards of middle- and high-income countries," said Martin Ravallion, director of the Bank's Research Group and head of the team that produced the report.
"This bunching up just above the extreme poverty line is indicative of the vulnerability facing a great many poor people in the world," Ravallion warned. "At the current rate of progress, around one billion people would still live in extreme poverty in 2015."
By region, in East Asia and the Pacific -- including China -- about 14 percent of the population were poor in 2008, down from 77 percent in 1981, when it was the region with the highest poverty rate in the world.
In South Asia, the poverty rate fell from 61 percent to 36 percent between 1981 and 2005, and dropped a further 3.5 percentage points between 2005 and 2008.
In Latin America and the Caribbean, while 14 percent of the population was poor in 1984, by 2008 that dropped to 6.5 percent. "The number of the poor rose until 2002 and has been falling sharply since," the report said.
In the Middle East and North Africa, 8.6 million people, or nearly three percent of the population, lived in poverty in 2008, down from 16.5 million in 1981.
The number of poor in eastern Europe and central Asia peaked in 1999 at nearly four percent, but has since dropped to less than 0.5 percent.
And in sub-Saharan Africa, 51 percent of the population lived in poverty in 1981, compared to 47 percent today.
The study ends in 2008 because more recent data from developing countries is either limited or not comparable with previous estimates.
Post-2008 studies, however, indicate that global poverty overall kept falling.