The Philippines' largest gold mine said Tuesday it was struggling to contain a waste spillage from its tailings dam which has forced it to suspend operations for the past month.

The last of a series of leaks at the Padcal mine occurred on August 30 and lasted nearly four hours, Philex Mining said in a disclosure statement to the Philippine Stock Exchange.

"We confirm that this discharge has been the fourth reported since the first incident that occurred on August 1," it added.

The company and the government had no immediate estimates on how much waste had entered the river systems around the mine, located near the northern resort city of Baguio in the Cordillera mountain range.

The environment department has ruled Philex cannot resume production unless the leak is plugged.

Its stock has been hit, trading at 18.98 pesos (45.33 US cents) Tuesday from 21.95 pesos before the leak was made public on August 3.

Chief regulator Leo Jasareno, head of the environment department's Mines and Geosciences Bureau, told AFP the miner was under state orders to plug the leak immediately, but added neither side could give a timetable.

"These spills are minor ones because the leak (from the August 1 accident) had not been fully plugged," Jasareno said.

Philex was trying to finish a drill hole from where cement would be poured to seal the leak, but bad weather was hampering the effort, he added.

Jasareno and Philex declined to comment on local press reports that up to 6.5 million tonnes of tailings had drained from the Padcal waste dam over the past month.

Jasareno said a government team was set to complete an official investigation next week, after which Philex would be assessed fines or other penalties for the discharge.

"Our current focus is towards the remediation and rehabilitation of the concerned penstock tunnel for which we have retained domestic and foreign third-party consultants to provide assistance," the company statement said.

Company spokesman Mike Toledo was unavailable for comment Tuesday, his office told AFP.

Earlier, Toledo stressed the spill was not toxic.

The accident came amid strong rains induced by Typhoon Saola and intense public debate about the mining industry in the Philippines, which is believed to have some of the biggest mineral reserves in the world.