COLOMBO (TIP): A human rights group on Thursday urged Sri Lanka to formally charge or release four university students detained on allegations of terrorism for honoring Tamil Tiger rebels who died during the country’s bloody civil war. The students in the northern city of Jaffna were arrested by anti-terrorism police for lighting lamps in honor of Tamil rebels to mark their annual heroes’ day on Nov. 27. This month they were transferred to a rehabilitation center housing former Tamil Tigers.

“Arresting four students without charge and sending them off for ‘rehabilitation’ sends a dangerous message that any Tamil can be detained arbitrarily and indefinitely,” said Brad Adams, Asia director for New York-based Human Rights Watch. “The Sri Lankan government needs to recognize that engaging in peaceful activities that conflict with the government’s views is an exercise of basic rights, not a criminal offense,” Adams said in a statement. Government soldiers defeated the rebels in 2009, ending a quartercentury bid to create an independent state for the country’s ethnic minority Tamils. Since then the government has razed rebels’ war burial grounds and prevented memorials including for civilians killed in the civil war.

Tens of thousands of civilians were estimated to have died in just the final five months of the conflict. The Liberation Tigers of Tamil Eelam was considered one of the most ruthless and effective terrorist groups in the world, highlighted by the use of suicide bombers and child soldiers. Memorials for their fallen cadres were held every year on Nov. 27, with highlight an annual speech by the rebel leader Velupillai Prabhakaran, who was killed by government troops in the final days of the war.

Government spokesman Keheliya Rambukwella said the students are being detained because they organized an event in honor of a banned organization. A government-appointed war commission recommended last year that war-affected civilians be allowed to organize peaceful memorials to promote post-war reconciliation. Ethnic Tamil politicians have criticized the government crackdown on memorials as a practice of double standards because memorials for those who took part in two Marxist insurrections in 1971 and 1988-89 are freely held every year. The Marxist rebels are mostly ethnic majority Sinhalese.