Bangladeshi soldiers recovered 10 more bodies in a second mass grave in a military compound in the capital Saturday, bringing to 76 the death toll from a mutiny staged by border guards over pay.
Some 50 officers were still missing, fire service operations chief Sheikh Mohammad Shahjalal said.
"We have so far removed 10 dead bodies. They are badly decomposed and many are mutilated," he said, adding the army was questioning some of the border security guards in custody about the whereabouts of those missing.
"They not only shot them dead but some bodies were badly mutilated with bayonets," Shahjalal said.
"It's beyond comprehension how one human could have done this to another."
Some of the dead may have been burned in the 33-hour revolt by rank-and-file border security troops that began early Wednesday and bones had been found, he added.
Rescuers uncovered Friday a first mass grave in the military compound that contained 38 bodies. Another 28 corpses were recovered in other parts of the compound, including in drains and sewers,
Most of the dead were senior military personnel, including the chief of the BDR. His wife's mutilated body was recovered Saturday.
The latest grave was discovered well hidden in the corner of a garden, Shahjalal said.
"We have to exercise extreme caution when removing these bodies because so many are disfigured. It's not just a matter of shovelling them out," he added.
A joint funeral for the military personnel was expected to be held once all bodies had been recovered. Three days of national mourning began Friday.
UN Secretary-General Ban Ki-moon described the deaths as "brutal acts of violence."
"The Secretary-General calls for calm and the resolution of this situation without further violence," said a statement released by his office, which expressed sympathy for victims and their families.
News of the grisly discoveries of the bodies filled the front-pages of Bangladesh newspapers. "Mass grave horror numbs nation," said a headline in the English-language Daily Star, which commented in an editorial that the "barbarity" of the deaths was "unimaginable, unforgivable."
The government, meanwhile, issued a new order to all troops belonging to the 70,000-strong Bangladesh Rifles (BDR) to return to their posts within 24 hours.
In a nationwide television address Saturday, the army's second-in-command said the rank-and-file guards who turned on their superiors would be punished.
"The BDR troops who took part in these barbaric and grisly acts cannot be pardoned and will not be pardoned," said Lieutenant General M.A. Mubin.
"They will be given exemplary and quick punishment by a special tribunal. The martyrs will be buried with state honours."
Tensions in the BDR had simmered for months but erupted into violence when senior officers rejected appeals for more pay, subsidised food and holidays.
The guards agreed to put down their arms after Prime Minister Sheikh Hasina -- who took office two months ago -- appeared on national television and threatened to put down the mutiny by force.
More than 200 BDR members were arrested Friday and police and army were conducting a nationwide search for those behind the revolt and killings. Twenty-two were arrested Saturday in the northern district of Tangail.
Sheikh Hasina, who had promised a general amnesty for those who surrendered, said those responsible for the deaths would be severely punished.
The violence was the first major crisis faced by the premier since her landslide election win December 29 ended two years of army-backed rule.
Dhaka University professor Ataur Rahman said the government could not afford to ignore the underlying causes of long-term discontent in Bangladesh, especially poverty and corruption.
"There are so many issues facing this country that it can be daunting for leaders, but they should not forget the issues facing the people," Rahman said.
Bangladesh has a history of political violence, coups and counter-coups since winning independence from Pakistan in 1971.
Already one of the world's poorest countries, it has been hurt by rising inflation, particularly for food, over the past two years.
