* 1 billion people live in hazard-prone slums, shantytowns

* Asia most at risk from deadly cyclones, tsunamis, floods

* U.N. says disasters threaten economic stability, security

GENEVA, May 17 (Reuters) - Natural disasters threaten to trigger widespread damage and distress in emerging economies, many of which are already on the brink because of the global recession, a United Nations body said on Sunday.

There are 1 billion people living in hazard-prone slums and shantytowns in developing countries, many of which overlooked safety standards in recent years of red-hot growth, according to the International Strategy for Disaster Reduction.

Crammed settlements with poor drainage systems are making floods more frequent and severe in many cities, particularly in Asia, where the ISDR said big swathes of commercial assets and infrastructure are also exposed to storms and earthquakes.

"Disaster risk is rising in an alarming way, threatening development gains, economic stability and global security," U.N. Secretary-General Ban Ki-moon said, introducing the 200-page report launched in Bahrain.

The Geneva-based ISDR estimated that the share of the global economy at direct risk from floods has doubled since 1990, and that 28 percent more people are now vulnerable to losing their homes, incomes and lives than two decades ago.

"Most flood risk is concentrated in Asian countries," it said, estimating that three quarters of those at risk of dying in floods around the world are concentrated in Bangladesh, India and China.

Thailand and Indonesia also face substantial threats from floods, the report said. Bangladesh was listed as facing the highest mortality risk from cyclones, along with China, India, the Philippines, Myanmar and Madagascar, while Ethiopia, Indonesia and India are most vulnerable to deadly landslides.

China and India are most at risk from deaths in earthquakes, followed by Indonesia, El Salvador, Guatemala and the Democratic Republic of Congo. Sub-Saharan African countries were cited as having the most people and crops exposed to risks from drought.

The poorest communities in developing countries are at highest risk from disasters and are rarely covered by insurance.

The ISDR estimated that 1.7 million people have been killed in 23 "mega disasters" since 1975, and said that major storms and weather-related emergencies are expected to increase as a result of global warming.

"Many urban areas will also experience stress through water and energy shortages, heat and cold waves and more prevalent disease vectors," it said, raising particular concern about the impact of rising oceans on Dhaka, Mumbai and Shanghai, large parts of which are only 1 to 5 metres above sea level.

The ISDR stressed it is not just geography that makes impoverished pockets of the world most vulnerable to disasters, saying that weak governance has made both people and economies in poorer countries more exposed to devastation.

For example, the report said while Japan and the Philippines have virtually the same exposure to tropical cyclones, they kill 17 times more people in the Philippines. Cyclones of the same strength also typically damage 20 times more of Madagascar's gross domestic product than Japan's.

It accused local officials worldwide of turning a blind eye to poorly built homes, schools and other buildings, and said governments in Africa, Asia and Latin America routinely ignore slums in low-lying and landslide-prone areas.

"Some low and middle-income countries which have experienced recent and rapid economic growth are more at risk from disaster because governance and construction standards have lagged and corruption is still rife," it said.

"Even in high income countries, problems persist as can be seen from last month's earthquake in Italy which destroyed a number of buildings constructed in modern times." (For more information about disaster risk reduction, see:

here

)