The company said it expected to make an announcement regarding Didipio by pre-open on Thursday.

Its shares plunged by more than 8% prior to the trading halt.

New Department of Environment and Natural Resources Secretary Gina Lopez took office in late June and initiated an environmental and social audit on the country’s mines.

At least 10 mines, mostly in nickel, had already been suspended and the final results of the audit were due to be handed down yesterday.

Reuters, citing a Philippines government source, reported this afternoon that another 20 mines had been suspended, including Didipio.

Didipio was not thought to be under threat of suspension, given it was the first ISO14001-certified mine in the Philippines.

Former President Benigno Aquino III named it the most environmentally responsible mine in the Philippines before he left office earlier this year.

Didipio produced around 90,000 ounces of gold in the first half of the year, as well as more than 12,000 tonnes of copper at all-in sustaining costs of just $US264 per ounce.

Open pit mining is expected to be completed by the end of next year before the operation goes underground.