Duterte stressed during the meeting of the Regional Peace and Order Council over the weekend that the SC decision would mean more security problems in the area, which has long been plagued by land ownership disputes.
Hundreds of people have been killed in clashes among mining firms operating at Mt. Diwalwal since gold exploration started there in the early 1980s.
"The latest SC decision would cause more trouble, especially among the thousands of small-scale miners who have depended on Mt. Diwalwal," Duterte said.
He said he expects the more than 40,000 small-scale miners at Mt. Diwalwal to protest the SC ruling.
Duterte, who chairs the Region 11 (Southern Mindanao) Peace and Order Council, said the government would have to find ways to beef up security at Mt. Diwalwal.
The security situation at the gold-rush site, where New People’s Army rebels have been collecting "revolutionary taxes," prompted the Armed Forces, among other reasons, to put up the Eastern Mindanao Command based here to address the communist insurgency, especially in communities near Mt. Diwalwal.
In a 32-page ruling, the SC reversed a March 13, 2002 decision of the Court of Appeals and declared that Exploration Permit 133 issued to Marcopper Mining Corp. has expired.
In effect, the exploration permit which Marcopper transferred in 1994 to its local subsidiary, the Southeastern Mindanao Gold Mining Corp., is void.
The SC decision cited the Mining Act of 1995 or Republic Act 7942 putting mining operations at Mt. Diwalwal entirely under the control of the government, which can either develop or explore the area’s resources itself or enter into agreements with certain individuals or companies for such purpose.
The SC ruling also ruled as illegal the Department of Environment and Natural Resources’ Administrative Order No. 66 issued in 1991 declaring 729 hectares within the gold-rush site a non-forest area, thus open to small-scale mining operations.
Meanwhile, the government reportedly lost nearly P300 million in potential revenue from the 85-15 sharing scheme it imposed at Mt. Diwalwal in 2002 due to the lack of manpower to collect its 15 percent share of mining proceeds.