Philippines officials are promising improved security for the nation's key mining industry after communist rebels overran three operations this week.

Officials said Tuesday that President Benigno Aquino has ordered a review of procedures at the nation's mines and that investors should be confident the perpetrators of Monday's attacks will be brought to justice.

However a presidential spokesman acknowledged the attacks have made it more difficult to go forward with peace negotiations with the New People's Army rebels.

The Maoist force, known for its extortion tactics, has been fighting to overthrow the government for more than 40 years. A new round of peace talks began earlier this year, but there is no cease-fire and the rebels have continued their attacks.

About 200 rebels were involved in Monday's attack on the nation's largest nickel producer and two other mines in Surigao del Norte province.

During the attack, the rebels disarmed company guards, briefly held company staff and set fire to offices and equipment.

The Philippines is looking to its mining sector to revive a long-stagnant economy as investors show increasing interest in its vast untapped reserves of minerals, including gold, copper and nickel. The government projects that mining investment will reach $18 billion by 2016, up from $3.8 billion over the past six years.