Thousands of people have died across the region this week in a relentless string of events that at first may seem to be the fault of Mother Nature, but the enormous death tolls can be equally blamed on people, they said.

Rafael Senga, a Filipino environmental expert with the World Wildlife Fund, said deforestation, the ever-expanding number of people living in dangerously planned cities and man-made induced climate change were all major problems.

"It's a combination of factors that can lead to a perfect storm for disaster in the region," said Senga. "The aggravating effect of environmental degradation, deforestation and climate change is massive."

In the Philippines, more than 270 people died as tropical storm Ketsana pounded the nation's capital, Manila, and the government was quick to point out that those rains were the heaviest in more than four decades.

But, in a flood-prone city, it was no surprise that many of the people killed were from over-crowded shanty towns built along rivers with extremely poor drainage.

Residents of Marikina town east of Manila, which was among those badly hit by the flooding, also noticed that the floodwaters were thickened by soil apparently washed down from surrounding mountains that had been logged.

"It was not water that flooded us. It was mud," said Joanna Remo, chief medical doctor at the Amang Rodriquez Medical Center in Marikina.

Meanwhile, thousands of people are believed to have died in the Indonesian city of Padang following a 7.6-magnitude earthquake on Wednesday.

But geologists have long said Padang was highly likely to suffer a major quake, yet it housed nearly a million people often in poorly constructed buildings.

Similarly, parents blamed poorly constructed school buildings for the large number of deaths among children in last year's quake that hit Sichuan province, China, and killed 87,000 people in total.

The inexorable urbanisation of Asia brings with it a myriad of problems that exacerbate natural disasters, experts say.

"The outcome of Asia's high rate of urbanisation has been the expansion of urban populations into geographic areas, which are frequently affected by disaster events," the Bangkok-based Asian Disaster Preparedness Centre said on its website.

"The result is an increased vulnerability of populations and infrastructure." It said mitigation measures such as earthquake and cyclone-resistant buildings, flood and landslide control measures and the incorporation of disaster vulnerability into land-use planning "have rarely been attempted in most Asian countries."

That problem is likely to worsen.

By 2030, five billion people worldwide are projected to live in urban areas, up from 3.3 billion in 2008, according to the Asian Development Bank.

The number of cities with populations of more than one million each are expected to jump to more than 500, up from only 11 from the beginning of the last century, it said, citing UN figures.

More than half of those cities will be in Asia, it added.

A Singapore-based regional economist said Asia's "reckless path" to economic development as well as corruption should also be blamed for the high number of casualties in disasters.

"In the rush to achieve high economic growth, short-cuts are sometimes taken," said the economist who asked not to be named because his company had businesses in the countries involved.

In 2007, 75% of all people killed from natural calamities came from Asia, the global charity World Vision said in a report late last year.