Sri Lanka's Human Rights Commission said on Friday that complaints of abuse against the army have grown since dozens of troops were killed recently in suspected rebel attacks on the peninsula.
Rohitha Priyadarshina, the commission’s regional co-ordinator, said: "After those attacks, we have been getting more complaints. Some report missing people, some were arrested by the army."
Other residents have reported being beaten up at army checkpoints, he said.
Of nearly 30 complaints of missing people, the commission was able to trace the individuals in all but four cases. Their families said they had all been taken by the army.
The military says Liberation Tigers of Tamil Eelam (LTTE) rebels, who have threatened to resume the war unless they are granted wide autonomy in the north and east, are trying to goad the army into over-reacting to win international sympathy.
One officer said: "They shoot at us and hope that we will fire back. But we do not fire if there are other people in front of us. We only shoot if we can see the target."
Army officers say they are receiving intelligence about the rebels from residents and claim that three-quarters of the local population opposes the Tigers.
But many residents said they resent what they see as an army occupation. They feel sidelined economically by the southern Sinahlese and want to administer their own affairs.
Troops say they expect more attacks in the weeks to come, and possibly even a full-scale assault from rebel territory. The city of Jaffna, which was lost by the Tigers to the army in 1995, appears to be the rebels' main focus.
Analysts say regaining control of the city would be a key rebel objective if there is a resumption of the decades-old war, which killed more than 64,000 people before a truce in 2002.
Rise up and fight
The Human Rights Commission says it has received complaints that the Tigers are recruiting child soldiers and torturing people.
But on the streets of Jaffna, it is the army that is blamed for beatings, rape, harassment and theft, particularly after the recent attacks on troops.
"The violence is entirely instigated by the army," one local man told Reuters. "If they continue behaving like this, war will come. It looks as if, more than the LTTE, the people themselves will rise up and fight. We will definitely offer our support to the LTTE."