A renegade commander has sought help from Sri Lanka’s peace broker Norway to ensure his safety after leading a shock breakaway from the Tamil Tigers, rebel sources said today.Aides of V. Muralitharan, better known by his nom de guerre Karuna, said he had asked for Norwegian help to guarantee his security following his split from the LTTE. ‘‘The Norwegians have been sounded out about the security concerns,’’ a rebel source in Karuna’s stronghold of Batticaloa said. The Norwegian Embassy here declined to comment. Meanwhile, Sri Lanka rejected a call by Karuna for a defence pact and a fresh ceasefire replacing the truce arranged by Norway. Defence Secretary Cyril Herath said: ‘‘We cannot agree to that when there is one ceasefire agreement signed between the PM and (Tiger leader Velupillai) Prabhakaran.’’ Karuna’s request yesterday was the first sign that he had split from the movement which prides itself on its zero tolerance for dissent.