Ageing Muslim rebel leaders in the southern Philippines are voicing growing frustration that efforts to end one of Asia's longest and deadliest insurgencies have hit another diplomatic brick wall. - File photo

MANILA: Philippine President Benigno Aquino III has ordered security for mining companies beefed up after a big raid by communist rebels shut down operations of the country's largest nickel producer and sent its stock plummeting.

Following the president's instructions, Interior Secretary Jesse Robredo said Tuesday that troops and government-armed civilian militiamen will be sent to improve security for mining operators in remote southern areas.

Communist guerrillas burned down scores of heavy equipment, disarmed guards and briefly held company staff at the three mines in Surigao del Norte province Monday.

Shares of Nickel Asia Corp. dropped by 13 percent in early trading Tuesday after the mine operator suspended activities because of the attack.