Four mining workers have been killed in an explosion that ripped through a gold mine shaft in southern Philippines.
The mine is located in a gold-rich village of Pamintaran in Mindanao's Compostela Valley province, which is around 1,000km south-east of capital Manila.
A state-run Davao Regional Hospital (DRH) staff was quoted by Xinhua News Agency as saying that all the four male victims succumbed to gas poisoning following a dynamite explosion in an adjacent tunnel.
The incident happened at around 8.30pm local time, the agency reported citing the DRH staff, who also provided identities of the deceased miners.
Around 50,000 people, who reside in the minerals-rich Compostela Valley, are dependent on small-scale illegal mining.
With operations of most of these small-scale mines being unregulated, landslide and cave-in accidents related to industrial explosion happen regularly in these mines, according to the agency.
Philippines suffered another gas poisoning incident two weeks ago, inside a pocket mining tunnel in Sitio Tumtumba Macannawey in Barangay Cabiten, which left two miners died and left six others injured.
Earlier this month, an alliance of environmentalists Save Sierra Madre Network Alliance (SSMNA) raised concerns on the unregulated small-scale gold mining industry in country's Angat and Marikina watersheds.
SSMNA chairman Elizabeth Carranza said: "Small-scale gold mining operations are scattered in different watersheds and river systems of Sierra Madre.
"Since no government body has been monitoring these mining operations, miners are releasing toxic mercury into the waters."