Malaysian Prime Minister Najib Razak has rejected a self-styled Sulu Sultan Jamalul Kiram III's offer of a unilateral ceasefire, warning him to surrender or face a military crackdown.
Sulu militants must lay down arms and surrender unconditionally and operations against them "will go on as long as it takes," Najib said at a press conference on Thursday.
The 74-year-old Jamalul claims he is the head of the Islamic Sultanate of Sulu, which once controlled parts of Borneo including the site of the stand-off, as well as southern Philippine islands.
"Sabah is a part of Malaysia and in the Cobbold Commission, more than two-thirds of the people in the state voiced their intention to be part of this nation (in 1963)," Najib stressed as he had closer look at the offensive against the Sulu gunmen, which entered its third day on Thursday.
"So the question about Sabah being part of Malaysia cannot be disputed by anyone inside or outside this country. And we will defend this position," he said.
Meanwhile, the fate of Sulu armed group leader Azzimudie Kiram remained unknown as Malaysian elite military and police teams entered into the final stage of search and mopping up operations at two villages on Friday.
Azzimudie, the brother of Jamalul, has failed to contact the Kiram family in Manila for the past two days and security forces expect to know what happened to him in a day or two.
The so-called Royal Sulu Army general identified as Haji Musa was among the some 30 gunmen killed in a shootout at Kampung Tanjung Batu on Wednesday.
Malaysian security forces launched an all-out offensive against the intruders on Tuesday, after a stand-off that began on February 9 by the armed intruders from southern Philippines who were supporters of an erstwhile Muslim Sultan and were laying claim to the sprawling territory where they were holed up saying it belonged to their royal heritage.
The United Nations Secretary-General Ban Ki-moon has called for an end to the violence in Sabah and asked for dialogue among all the parties involved for a peaceful resolution.
Malaysian security forces on Tuesday launched an air strike using F-18 and Hawk fighter jets in the first operation to end the intrusion by Filipino gunmen who have holed up in Lahad Datu, Sabah since February 12.
Meanwhile, Opposition leader Anwar Ibrahim has filed a 100 million ringgit suit against a local TV station over reports alleging he had links to Lahad Datu intrusion.
On Thursday, he told Radyo Inquirer 990AM that the presence of insurgents was "unacceptable" and blamed the local mainstream media for spinning the issue.