At least 36 people were killed and 72 wounded in southwestern Nepal when a powerful bomb ripped through a crowded passenger bus in one of the bloodiest attacks on civilians by suspected Maoist rebels since their revolt began nine years ago.

“At least 36 civilians were killed and 72 others injured when the terrorists blasted their bus with a landmine at Madi in Chitwan,” the army said in a statement.

Earlier state-run radio, quoting police, had put the death toll at more than 50 people.

An army officer told AFP the bus was torn apart by the force of the blast and that the passengers were badly mutilated by shrapnel as well as by shards of metal and glass from the bus.

“[The bus] rose into the air… quite high and came down and split into two,” the officer said, quoting witnesses.

The radio report, quoting police superintendent Surendra Bahadur Shah, said 16 seriously injured people had been transferred to hospitals in Kathmandu for treatment.

Shah said the attack was the work of “terrorists”, a word which the police and military in Nepal use to describe Maoist rebels.

Officials said many of the victims were women and children, and that three military personnel on their way home for vacation were among the dead.

The blast occurred at Madi village in the Maoist-controlled district of Chitwan, about 180 kilometres (113 miles) southwest of Kathmandu, early on Monday morning.

The military cordoned off the scene so that medics and family members could search for items that could prove helpful in identifying some of the victims, officials said.

Search operations for the culprits were also under way throughout the district, they said.

Witnesses at the scene said the explosion left a hole in the dirt road five feet (1.5 metres) across. The charred and twisted bus had been pulled into a nearby field.

The army said the rebels placed as much as 50 kilograms (23 pounds) of high explosives in a container buried underneath the road and remotely detonated it as the bus passed, crammed with more than 100 passengers inside and outside on the roof.

“The terrorists knew that very few vehicles operated on the route and despite the fact that they could see a lot of people travelling inside and on the rooftop of bus, they blasted it,” the army statement said.

UN Secretary General Kofi Annan called the deaths senseless.

In a UN spokesman’s written statement, Annan called “for an immediate end to such utterly reprehensible tactics that expose civilians to danger in the conflict in Nepal.”

There was no immediate claim of responsibility from the Maoists, who have been fighting to install a communist republic in Nepal since 1996. The insurgency has already claimed more than 11,000 lives.

The rebels are generally not known for launching indiscriminate bombings of civilian targets, although they have been accused by human rights groups of the torture and murder of villagers they believe to be collaborating with the armed forces.

The Maoists have stepped up their campaign through road blockades and attacks on troops since King Gyanendra sacked the coalition government, imposed a state of emergency and assumed absolute power on February 1, saying the moves were necessary to tackle the insurgency.

Army spokesman Brigadier General Dipak Gurung said last month the security situation in Nepal was “definitely better today” than before the king sacked the government for failing to control the Maoists and hold elections.

“We are able to focus more on our main job” of fighting the insurgency rather than containing civilian disturbances, said the general. — AFP