KOHIMA, March 18 ? The NSCN (I-M) today said the killing of 11 of its cadres in an encounter in Manipur was an ?act of barbarism? and urged the Centre to clarify its stand on the incident and book the culprits to uphold the current Naga peace process and prevent ?undesirable reprisals,? reports PTI. Condemning the killings of its cadres in Chandel district yesterday, Information and Publicity wing of the underground outfit in a statement here claimed their cadres were on their way to celebrate ?Naga Republic Day?, when the India Reserve Battalion (IRB) personnel allegedly ambushed them. Reports form Imphal, quoting official sources, had said the NSCN(I-M) members were killed in an encounter with the police and IRB personnel when the militants opened fire on the security personnel at Pallel area, when asked to stop their hijacked mini truck. The outfit alleged that the act ?highly reflected? the gravity of ?barbarism of Indian draconian laws? flouting the cessation of all hostilities as per the ?Ceasefire Agreement?. Although the Ceasefire between security forces and NSCN (I-M) has been in force in Nagaland since August 1997, it is not official between the two sides in states neighbouring Nagaland. Demanding an immediate clarification from the Centre, the NSCN (I-M) statement maintained: ?It (incident) is an insult? to the Naga ceasefire and the subsequent peace process.