MANILA, Philippines - Three alleged supporters of Sulu Sultan Jamalul Kiram III and a Malaysian soldier were killed in a fresh outbreak of violence in Lahad Datu, Sabah on Tuesday, Malaysian authorities said.

The fighting occurred near Kampung Tanjung Batu, as Malaysian troops continued their "mopping-up" operations, Malaysia's General Zulkefli Zin said.

The firefight broke out when security forces spotted a group of 5 gunmen in the area, he said in a press conference, according to a report by Malaysian news website The Star Online.

"They had a gun fight with five armed men who then retreated," he said. "In the exchange of fire a soldier and three terrorists were killed."

More bodies were also discovered Tuesday in in Kampung Tanduo by Malaysian security forces, according to the New Straits Times.

Fifteen decomposing bodies, who allegedly belong to Kiram's royal army, were found in the area, Sabah police commissioner Hamza Taib said.

"Initially our forensic and crime investigation department team had found nine bodies but I've instructed my men to go to the area this morning to confirm the figure as we believe there are more than nine bodies," he added.

"These are the Sulu gunmen shot on March 1. Earlier we confirmed that 12 were gunned down but yesterday, we were told there are 15 decomposed bodies. There could be more," Hamza told reporters.

Authorities did not provide an overall death toll from the month-long drama, but reports and government statements had indicated an earlier count of 63 killed prior to Tuesday's clash -- mostly intruders.

The sultan's armed supporters landed in Sabah last month to assert a long-dormant claim on the region, stunning Malaysia and injecting tension into ties between the two neighbours.

After a three-week standoff in a sleepy farming village surrounded by palm oil plantations, a violent shootout triggered a Malaysian armed forces attack March 5 that sent the gunmen into hiding in surrounding farmland and a nearby village.

Police also said Tuesday they had confirmed that a militant killed earlier was one of the group's top leaders, identified by Malaysian media as Haji Musa, a former commander with the Moro National Liberation Front (MNLF).

The MNLF had waged a rebellion against the Philippine government in the country's Muslim south until signing a peace deal in 1996.

Eight police officers were killed in earlier shootouts, and security forces also shot dead a teenager over the weekend. It has not been made clear whether the boy was a local or linked to the militants.

Authorities have also arrested at least 97 people throughout the state and are investigating if they have links to the incursion. They have not revealed any further details.

Supporters of Manila-based Kiram, whose supporters claim he is heir to the defunct southern Philippine sultanate of Sulu, have said about 235 people took part in the mission. - with a report from Agence France-Presse