Philippine security officials have launched a manhunt for two kidnapped Chinese businessmen in a mountainous town in the strife-torn south, a military spokesman said on Friday.

The gang that kidnapped the two is believed to have hidden the businessmen in Naga, a town near the coast in the restive southern island of Mindanao, said Captain Albert Caber.

"Our sources said that is where they always hide their victims... so our troops and the national police are there," he told AFP, adding that patrol boats sailing from Naga were being checked.

But he conceded the search for the victims, known locally as James Lou and Jampong Linyuan Kai, would not be easy.

The kidnappers "know it will be hard for authorities to find them. It is a mountainous area and there are many paths which can throw pursuers off," Caber said.

The two Guangdong natives were snatched late Monday from the town of Kabasalan, where they had lived for almost two years, buying manganese ore from local miners.

Former Muslim guerrilla-turned-bandit leader Waning Abdulsalam is believed to be behind the abduction.

Islamic extremists and former Muslim rebels in the southern Philippines have often resorted to kidnappings to raise money, targeting both locals and foreigners.

An Australian man seized in December 2011 and two European birdwatchers abducted in February are among at least five other foreigners still believed to be in the hands of kidnappers in the Mindanao region.

[Photo via AFP]