The leader of rebels who had infiltrated Sabah Island last month has called for a unilateral ceasefire after a major offensive by Malaysian troops.
Jamalul Kiram III, a self-proclaimed Philippine sultan, declared a unilateral ceasefire to be effective from 12:30pm local time (04:30GMT) and urged Malaysia to reciprocate, according to a statement read out by his spokesman in the Philippine capital, Manila, on Thursday.
"They will not take any action. They will remain in the place where they are now. They will not expand operations," a spokesman said, referring to the rebels, believed to number between 100 and 300.
The spokesman, Abraham Idjirani, said Kiram was responding to a call by UN Secretary General Ban Ki-moon on Wednesday in which he urged an end to the violence in the Malaysian state and encourage dialogue between the opposing sides.
"The sultan is calling for a unilateral ceasefire... in order to reciprocate the call of the UN to preserve lives," said Idjirani, as the elderly and ailing Kiram sat next to him.
"We hope Malaysia reciprocates the same call for a ceasefire."
Kiram sent his followers from the southern Philippine province of Sulu to assert an ancestral claim.
At least 28 people, mostly rebels, have reported been killed since the stand-off began more than three weeks ago.
Malaysia launched an air and ground attack on Tuesday aimed at crushing the fighters who call themselves 'royal Sulu army'.
But the assault failed to eliminate the armed fighters, and Malaysian security forces continued on Thursday to scour the region of vast palm plantations and jungles for them.
Kiram says he is the current Sultan of Sulu, although the sultanate no longer has any formal power in the Philippines.
He said his men went to Sabah to assert their claim to the area, citing ownership documents from the late 1800s.
The Sulu sultanate's power faded about a century ago but it has continued to receive nominal payments from Malaysia for Sabah under a historical lease arrangement passed down from European colonial powers.