Colombo, Aug. 31 (Reuters): The UN threatened overnight to suspend aid operations in Sri Lanka after truce monitors accused the security forces of executing aid workers.

Nordic truce monitors yesterday formally accused the security forces of being behind the execution-style murders of 17 local staff of aid agency Action Contre La Faim earlier this month in the northeast. The government denies it, and angry officials accused the monitors of being biased towards the rebels in their ruling.

“We have no independent information ourselves in the UN, but I say we cannot continue in this area unless people will be held accountable for the execution of 17 of our colleagues,” the UN Emergency Relief Coordinator, Jan Egeland, said in New York.

The victims, mostly Tamils, were found shot dead in their compound in the northeastern town of Mutur, around 220 km northeast of Colombo.

It was the worst mass murder of aid staff since a 2003 bomb attack on the UN compound in Baghdad.

The Nordic Sri Lanka Monitoring Mission, which oversees a 2002 truce that now only holds on paper, says Sri Lankan authorities have obstructed their efforts to investigate, and says it is convinced no armed groups other than the security services could have been responsible. “I will have some problems to trust a government investigation now because they are too involved in this case,” outgoing chief monitor Major General Ulf Henricsson said.

“A democratic and accountable government should support an international commission to look into this case.”

“This is not just a Sri Lankan problem. This is a worldwide problem if you can kill aid workers without any punishment.”

Eric Schwartz, former President Bill Clinton’s deputy UN special envoy for tsunami recovery who is visiting the island, has called on the government to guarantee the safety of aid workers.