Many people reported dead in a recent bombing in Afghanistan were actually shot dead by security guards after the blast, an internal UN document says.
The blast happened in a region not known for suicide attacks
The report said that guards protecting Afghan MPs had fired "deliberately and indiscriminately" into crowds of civilians in northern Baghlan province.
Dozens were killed in Baghlan on 6 November, most of them schoolchildren who had gathered to greet MPs.
The attack was one of the bloodiest in Afghanistan's history.
The UN mission in Afghanistan said its leaked report was not complete and had not been officially endorsed.
A copy of the report by the UN Department of Safety and Security was obtained by The Associated Press news agency.
The document said it was unclear how many of the 77 people who died were killed by the bomb and how many by shooting afterwards.
"Regardless of what the exact breakdown of numbers may be, the fact remains that a number of armed men deliberately and indiscriminately fired into a crowd of unarmed civilians that posed no threat to them, causing multiple deaths and injuries," the report said, according to AP.
"It is believed that at least 100 rounds or more were fired into the crowd with a separate group of schoolchildren off to one side of the road bearing the brunt of the onslaught at close range."
Correspondents say the report is part of the UN's weekly security assessment, and is not a separate UN investigation into events in Baghlan.
Two Afghan government investigations are already under way.
KEY BOMB ATTACKS SINCE 2001
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3 Aug 2006
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16 Jan 2006
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1 June 2005
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UN spokesman Dan McNorton said the AP story was "premature and is based on incomplete information".
"At the moment, there is real uncertainty," he said in a statement.
"We have to be sure [about the final outcome of the Afghan investigations] before we can make a statement on it.
"We would support giving the authorities time to allow their investigations to run their course."
The Afghan authorities say a suicide bomber carried out the attack with a bomb packed full of ball bearings to inflict maximum casualties.
The bomb exploded at a sugar factory in a town in Baghlan province while a delegation of parliamentarians was visiting.
Among MPs killed was Mustafa Kazimi, a former mujahideen fighter and prominent opposition figure.
It is not clear who carried out the attack. The Taleban denied responsibility.