Twelve Nepalese hostages have been killed by their captors in Iraq.
The bodies shown on an Islamic website
A Nepalese diplomat confirmed the deaths hours after images were put on a website, apparently showing one man being beheaded and 11 being shot dead.
Nepal's ambassador to Qatar, Shyamanand Suman, said it was one of the "worst days" in his country's history.
The militants said the 12 Nepalis had been killed because they "came from their country to fight the Muslims and to serve the Jews and the Christians".
The group, Army of Ansar al-Sunna, said the men were being punished for helping the US, and it had "carried out the sentence of God" against them.
Mr Suman told Radio Nepal that he did not yet know all the details of the killings but did believe the men were dead.
"I have contacted Cairo and I have received confirmation. Confirmation has come from different quarters," he said.
No remains of the hostages have yet been recovered.
Many foreigners have been captured in Iraq and some have been killed, but this is by far the largest killing of hostages.
Among at least 20 people still being held by militants are two French journalists whose captors have given France until Tuesday evening to revoke a ban on Islamic headscarves in state schools.
The 12 Nepalese citizens are thought to have travelled to the Middle East to earn money as cooks and cleaners.
Ramesh Khadka's mother fainted at the news of her son's death
A video on a website used by Islamic militants showed two men holding down an apparent hostage and beheading him.
It also showed a group of men lying on the ground who were then shot in the back and the head.
In Nepal, the government held an emergency Cabinet meeting in the capital Kathmandu.
It condemned the murders as a "barbarian act of terrorism", and pressed the international community to hunt down the killers.
Elsewhere, the men's families were grief-stricken.
"What sins have I committed to deserve this?" Jit Bahadur Khadka, father of hostage Ramesh, was quoted as saying by the Associated Press news agency in Kathmandu.
His wife Radha fainted at the news.
Villagers crowded round the family home in Lele, 20km (12 miles) south of Kathmandu, where the 19-year-old hostage had lived, to console them.
"We were expecting their safe return. This is very shocking.
This is completely unexpected," said Sudarshan Khadka, Ramesh's brother.
He said the Nepalese government had not done enough to get the men released.
But Nepal said it had tried to make contact with the hostage-takers.
Foreign Minister Prakash Sharan Mahat said the killings came as a shock because "there were no demands or deadlines."
He said he had stressed that Nepal was not part of the US-led coalition in Iraq.
One of the hostages was shown on an earlier video
"I repeatedly conveyed the message that these people have nothing to do with the Americans," he said.
The Kathmandu government accused recruitment agencies of putting impoverished Nepalese workers at risk in Iraq.
It vowed "to take action against those
persons who are found involved in illegal methods of recruitment of helpless Nepalese into Iraq, resulting in this devastating tragedy".
Nepal, one of the poorest countries in the world, has banned Nepalis from going to Iraq, despite the relatively well-paid jobs there.