(CNN) -- A day after launching airstrikes and mortar shells in a remote part of the island of Borneo, Malaysian security forces searched house-to-house Wednesday for gunmen from the Philippines who infiltrated the area last month and clashed with police.
The group of Filipino men is believed to number between 100 and 300.
It arrived three weeks ago on the east coast of the Malaysian state of Sabah, on Borneo, demanding recognition as representatives of an old sultanate that ruled the area.
Efforts by Malaysian and Philippine authorities to persuade the men to return peacefully to their homes in the nearby southern Philippines failed, and the standoff descended into clashes last week that reportedly left 28 people dead, including nine police officers.
Malaysian security forces said their offensive Tuesday, which involved fighter jets, mortars and ground troops, achieved its objectives.
However, they did not disclose the number of Filipino fighters captured or killed in the operation, and the Filipino group said the Malaysian attack failed to inflict any casualties.
On Wednesday, Malaysian police and armed forces combed the area around Kampung Tanduo, the village where the Filipinos had originally been holed up, in an attempt to flush out the gunmen, according to Bernama, Malaysia's national news agency.
Alarm in Malaysia
The crisis in Sabah alarmed Malaysians over the ease with which the intruders entered the country from the nearby southern Philippines, where a number of Muslim rebel groups are based.
It has also revived an unresolved territorial issue between the Philippines and Malaysia.
The Malaysian forces' task of tracking down the gunmen has been complicated by the Filipinos' efforts to blend in with the local population, Ismail Omar, the head of Malaysian Police, said at a news conference Wednesday, according to Bernama.
Ismail said one gunman was believed fatally shot early Wednesday after ambushing Malaysian security forces, but that the other attackers had retrieved his body.
There are strong ethnic ties between many inhabitants of Sabah and the southern Philippines. People and goods regularly go back and forth across the porous sea border between the two.
The Filipino men have called themselves the Royal Army of the Sultanate of Sulu, a former Islamic power in the region that once controlled parts of the Philippines and Borneo. Its influence has since faded, and it is now a clan in the restive southern Philippines.
The sultanate's leadership has been driven by internal power struggles in recent decades, but the squabbling family members appear to have united in the recent decision to send their followers to Sabah and stake a claim to their former territory.
Abraham Idjirani, a spokesman for one of the sultanate's leaders in Manila, said he had spoken twice Wednesday with the leader of the armed group in Sabah, who reported that the men were in "good condition" and prepared for another possible attack.
He claimed the group had suffered no casualties from the assault Tuesday because the Malaysian planes had bombed an area vacated by Filipinos.
The sultanate is still open to talks, but the group in Sabah will not return to the Philippines, Idjirani said.
The situation on the ground appears to be getting more complex with reports that other Filipino fighters, sympathetic to the sultanate's cause, are joining the group in Sabah, despite efforts by Malaysia and the Philippines to tighten sea patrols in the area.
Idjirani said Tuesday that other people from the region were joining the sultanate's followers, although he didn't know who they were.
And Nur Misuari, a founding leader of the Moro National Liberation Front (MNLF), a Muslim rebel group that signed a peace deal with the Philippine government in 1996 after decades of armed rebellion, said he believed former fighters from the organization were with the sultanate's followers in Sabah.
He said if any current MNLF members had gone there, they had done so without authorization.
A faded power
Established in the 15th century, the Sultanate of Sulu became an Islamic power center in Southeast Asia that at one point ruled Sabah.
But the encroachment of Western colonial powers, followed by the emergence of the Philippines and Malaysia as independent nation states, steadily eroded the sultanate's influence. Sulu is now a province within the Republic of the Philippines.
But the historical connection still fuels tensions between Malaysia and the Philippines, with Manila retaining a "dormant claim" to Sabah through the Sultanate of Sulu, according to the CIA World Factbook.
The Philippines claims much of the eastern part of Sabah, which was leased to the British North Borneo Company in 1878 by the Sultanate of Sulu. In 1963, Britain transferred Sabah to Malaysia, a move that the sultanate claimed was a breach of the 1878 deal.
Malaysia still pays a token rent to the sultanate for the lease of Sabah.