Members of the Manobo tribe seized the hostages who include several minors from a number of schools in La Prosperidad, on the southern island of Mindanao on Friday, a police official and the local mayor said.

Alvin Magdamit, mayor of La Prosperidad, said a negotiating team was in contact with the kidnappers' leader Reyjoy Brital.

Speaking to negotiators by cellphone, Brital threatened to kill the captives if a rescue attempt was launched.

"They should behave because if they continue to come into our area we will make an example out of the hostages," Brital was heard saying in the local dialect.

Brital, a former communist insurgent who later returned to legal activities, is demanding the release of fellow tribesman Ondo Perez, who was jailed for kidnapping 79 people in 2009.

Government negotiators had promised not to arrest Perez if he freed his hostages but police seized him once they were released.

The head of the regional police Chief Superintendent Reynaldo Rafal said negotiations, led by Magdamit, were continuing.

Brital again threatened to kill the hostages when told his demand would not be met.