The findings were published in the United Nations Human Development Report, released on Tuesday.
Foreign aid dropped during the 1990s, debt increased for poor nations, AIDS statistics soared and prices for crucial commodities, the main exports from poor nations, fell according to the report.
"In this so-called great decade, a very significant hard core of countries ended further behind with more poor people," said Mark Malloch Brown, who heads the UN Development Programme.
Fifty-four countries, almost half of them in Africa, are poorer now than in 1990.
This year's survey documented the progress of 175 countries toward eight UN Millennium development goals agreed to by world leaders three years ago.
The goals ranged from reducing extreme poverty to halting the spread of Aids by 2015.
The report stated that for Arab states, Latin America and the Caribbean, reaching the goals by 2015 is possible.
But the report's findings for Africa were dismal.
It will take 20 sub-Saharan African nations until 2129 to achieve universal primary education, until 2147 to halve extreme poverty and until 2165 to cut child mortality by two-thirds.
The report urged that foreign aid be doubled to $100 billion annually.
"Every European cow is getting a $3 a day subsidy whereas 40 percent of Africans live on less than $1 a day," said Malloch.
Change of view
"Every European cow is getting a $3 a day subsidy whereas 40 percent of Africans live on less than $1 a day"
Mark Malloch Brown,
UN Development Programme
The UN report argued for a broader view of how to lift the least developed nations out of extreme poverty, instead of the "Washington consensus" of the World Bank and International Monetary Fund (IMF).
It said a single set of policies for all countries could do more harm.
"The IMF and the World Bank should no longer set these kind of ceilings," said Brown.
Meanwhile, Canada, which had been first place in the quality of life index report for seven years, dropped to the eighth rank this year.
Last year Canada dropped to the third position.
Norway, Iceland, Sweden, Australia and the Netherlands ranked as the best countries, while the United States and Canada secured the seventh and eighth positions respectively.
The report analyses factors including per-capita income, education levels, health care and life expectancy in measuring a nation’s well-being.
The report also gives a separate index for women’s participation in political and economic fields, with unexpected results-women in Botswana, Costa Rica and Namibia fare better than in Greece, Italy and Japan.