RIO DE JANEIRO (Reuters) - Almost a quarter of a billion people moved out of slum conditions in the past decade, driven by rapid economic growth in emerging giants India and China, but the number of people living in them continues to rise, the United Nations housing agency said on Friday.

A view of Rocinha shantytown in Rio de Janeiro November 2, 2005. REUTERS/Bruno Domingos

The number of people living in shantytowns increased by 55 million to 827.6 million as population growth and migration from the countryside outstripped the effect of upward mobility in cities, the U.N.’s biennial report on cities found.

“The situation has improved over 10 years, but alas over the same period, the net increase of the urban poor is 55 million,” Anna Tibaijuka, the executive director of the U.N. Habitat program, said in Rio de Janeiro.

The Brazilian city will next week host the World Urban Forum, a five-day U.N. conference on the state of the world’s cities, where more than half the global population now lives.

Some 227 million people escaped slum conditions from 2000 to 2010, meaning that countries easily surpassed their collective target under the U.N. Millennium Development target, the report said.

Tibaijuka played down the achievement of beating the Millennium goal of pulling 100 million people out of poverty, calling it “totally inadequate.” The Millennium goals include cutting extreme poverty, reducing child mortality and fighting epidemics by 2015.

Barring “drastic” action, the number of slum dwellers in the world’s cities is expected to grow by 6 million a year over the next decade to hit 889 million by 2020, the report said.

China’s pro-growth policies had helped to cut the number of slum dwellers there by a quarter over the decade, while India achieved a reduction of a third. Together, at least 125 million people were lifted out of poverty in the two emerging giants, the report found.

In Latin America, Brazil led the way in absolute poverty reduction as 10.4 million people left slum conditions.

“In the Brazilian case, the main factor above all was basic sanitation, and above all in the northeast where the most significant advances occurred,” said Eduardo Lopez-Moreno, one of the report’s authors.