The scale of devastation in Haiti is far worse than in Asia after the 2004 tsunami, a study said Tuesday, predicting last month's quake could be the most destructive disaster in modern history.

The stark assessment from the Inter-American Development Bank (IDB) comes with Port-au-Prince still lying in ruins more than one month on, while the bodies of more than 200,000 dead pile up in mass graves outside the capital.

The study's release coincided with what would normally be Haiti's annual carnival, an explosion of pulsing music and colorful parades. But this year, the events have been cancelled as no one is in the mood to party.

The preliminary IDB report estimated the damage at between eight and 14 billion dollars in what was already the poorest country in the Americas before the catastrophe.

Factoring in Haiti's population and economic output, the upper estimate would make it the most destructive natural disaster in modern history, the bank said.

"Indeed, in this respect the Haiti earthquake was vastly more destructive than the Indonesian tsunami of 2004 and the cyclone that hit Myanmar in 2008," an IDB statement said.

"It caused five times more deaths per million inhabitants than the second-ranking natural killer, the 1972 earthquake in Nicaragua."

Haiti officials say more than 217,000 people were killed in the quake, or about 2.4 percent of the country's population of nine million.

The 14-billion-dollar figure is the Washington-based bank's upper estimate for the cost of reconstructing homes, schools, streets and other infrastructure in Haiti following the January 12 quake.

The IDB said a more detailed accounting of the situation would come in the following months but that its preliminary study showed that the reconstruction cost was likely to be far higher than anticipated.

Meanwhile, Haiti's carnival celebrations, usually the culmination of weeks of parties, were replaced by mourning.

"Everybody's sad," said Nanotte Verly, a 48-year-old mother of nine who lost her home in the quake and sells jewelry and wooden plaques praising Jesus on a roadside. "All the buildings are still collapsed on the ground."

More than a million Haitians are still homeless following the earthquake, living in squalid camps in and around the capital.

"There are a lot of people who lost relatives and who are not in a mood for celebrating," said Anel Sainterne, 21, an artist selling her paintings on the street.

Haiti's raucous carnival replaced by mourning

While aid workers rush to distribute tarpaulins before the rainy season starts, the United Nations says only about 272,000 people have been provided with shelter materials so far.

Fresh tragedy struck on Monday, when a school partially collapsed in the city of Cap-Haitien in the country's north after a mudslide caused by rain, killing four children.

The incident signaled the dangers that lie ahead with the coming rainy season, which typically starts around May. Aid workers have warned that the rains threaten to worsen the already poor conditions in makeshift camps.

Even as many sink deeper into despair, others seek to forget the trauma of the earthquake.

In the courtyard of a religious school in Petionville, a suburb of Port-au-Prince, 11-year-old Annelodie Mercuecs spends hours a day escaping the foul-smelling makeshift camps where she now lives with her parents.

"After the earthquake, I've done nothing. I come here to play with my friends," she said of the care center set up by the French Red Cross to bring a slice of normalcy to shattered young lives.

On his second day in Haiti to give a boost to the relief effort, Canadian Prime Minister Stephen Harper visited Canadian troops in Leogane, a town largely wiped out by the quake where the soldiers are helping set up a hospital.

Harper had earlier said Canada would set up a semi-permanent, 11-million-dollar headquarters for the Haitian government, which currently operates out of a police building because the palace and many government ministries were destroyed in the quake.

French President Nicolas Sarkozy was due to arrive here on Wednesday.