The man suffered a wound to the back of the head on Wednesday night in Trincomalee and was transferred to a hospital in Colombo, but his condition did not appear to be critical, Mercy Corps programme director Iveta Ouvry said.
The Filipino national was in Trincomalee on a field visit to monitor post-tsunami projects, the group said on Thursday. Police and the military initially said it was unclear who the gunman was.
"One of our sentries at a guard post ... sighted an unknown person trying to enter that area, and he has warned several times but he didn't stop, so he fired some warning shots," said Navy spokesman Commander D.K.P. Dassanayake.
"That fellow ran away. We followed him and found him at the Oceanic (hotel)," he added. "Only then we got to know he was a Filipino ... and belongs to one of the NGOs. He had a small scrape injury to his head, nothing serious."
He said the man had tried to enter a fenced off, restricted area near a naval detachment.
"In the dark you cannot see anybody, no? So if somebody is trying (to enter), we consider them as the enemy."
The Club Oceanic is popular with international aid workers visiting Trincomalee, an area where there has been fierce fighting between government forces and Tamil Tiger rebels.
The shooting comes after a series of unsolved attacks on aid workers.
It also comes a fortnight after two local volunteers of the Sri Lanka Red Cross were abducted from a train station in Colombo and were later found murdered.
International observers have criticised President Mahinda Rajapaksa's government for making little progress in probing a series of killings and abuses, including the massacre of 17 local staff of Action Contre La Faim (Action Against Hunger) in August 2006.
That was the worst attack on aid workers since a 2003 suicide bombing of the U.N. headquarters in Baghdad.
- Reuters - Thomson Reuters Foundation
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