MANILA – At least twelve people died in the latest clash between Malaysian forces and members of the Sulu sultanate royal army, a Malaysian news agency reported on Sunday evening.

Bernama said another Malaysian policeman was killed in an ambush that began late Saturday in Kampung Sri Jaya, Siminul, Semporna in Sabah, bringing the number of police fatalities to six.

"Their identities will be revealed to their respective families before being posted on the official website of the Royal Malaysian Police," Bernama quoted Inspector-General of Police, Tan Sri Ismail Omar, as saying.

The news agency also quoted Ismail as saying that 6 armed intruders were killed in the exchange of fire.

The report said a rescue operation that was launched following the ambush ended at 7 p.m. At least 19 policemen were rescued.

The slain policemen, Ismail said, were tasked to carry out an investigation in the village due to reports of presence of armed men. They were allegedly shot while approaching a house in the village.

Ismail also denied a claim by the sultanate that four Malaysian officials have been held hostage.

"This is just a rumor and I ask the public not to believe any rumor on the incident," Ismail said, adding that the situation in the village had returned to normal.

Friday clash

The shootout late Saturday in the town of Semporna followed a firefight a day earlier between Filipino followers of a self-proclaimed sultan and Malaysian security forces that left 12 intruders dead along with two police officers.

Semporna is 300 kilometers from Tanduo village, where an estimated 100 to 300 people have been encircled by Malaysian police and soldiers since landing by boat from the Philippines on February 12 to claim the area for their leader.

The 74-year-old Manila-based leader, Jamalul Kiram III, claims to be heir to the Islamic sultanate of Sulu, which once controlled parts of the southern Philippines and the modern-day Malaysian state of Sabah on Borneo island.

Malaysian officials called for calm but various reports painted a picture of chaos in the area.

It was not immediately made clear whether the Semporna attackers were still at large.

Meanwhile, Malaysian media quoted Ismail as saying police were pursuing yet another group of armed men in Kunak, another town in the region.

The new incidents sparked Malaysian fears of a wider campaign by other intruders or their supporters in Sabah, which has large numbers of Filipino immigrants -- both legal and illegal.

The Philippine embassy in Kuala Lumpur issued a statement urging calm among Filipinos. "We feel and understand the anxieties felt by many of you at these difficult times," it said. "This is not the time to undertake any action that might be misunderstood by some parties."

The situation is delicate for the Southeast Asian neighbors. The Philippine government is looking to consolidate recent progress in mending fences with Islamic separatists in its partly Muslim south.

The government of Muslim-majority Malaysia, meanwhile, could face pressure at home if harsh action is taken against the Islamic Filipino intruders, which also could inflame Sabah's many Filipinos.

Following Friday's firefight Malaysian police threatened "drastic action" if they did not surrender.

Kiram defiant

Philippine President Benigno Aquino III, who has sharply criticized the intruders, has also urged them to give up.

But Kiram's spokesman Abraham Idjirani repeated Sunday his followers would not budge. He said the sultan would seek the intervention of the United States, which colonized the Philippines in the early 1900s.

"(Malaysians) want to hide the truth -- that they do not own Sabah. It is owned by us," he said in an interview on Philippine radio.

Sabah state police chief Hamza Taib said several villagers in Semporna beat to death a man armed with a grenade launcher who had gathered several people at a mosque on Sunday, Malaysia's The Star newspaper reported.

The sensational events have embarrassed Malaysian Prime Minister Najib Razak -- who must call elections by June -- by exposing lax border security and fuelling perceptions of lawlessness and massive illegal immigration into Sabah.

Lim Kit Siang, a top opposition leader, said the government was not being forthcoming enough with information from Sabah and the police fatalities "could have been avoided if the whole situation had been properly handled".

The Sulu sultanate's power faded about a century ago but it has continued to receive nominal Malaysian payments for Sabah under a lease deal inherited from European colonial powers.

Kiram's people are demanding Malaysia recognize that the sultanate owns Sabah and share profits from economic development in the state. - with Agence France-Presse