If 20 mines eventually halted, will bring total closures to 30...

• If 20 mines eventually halted, will bring total closures to 30
• Threat of supply disruption underpins LME nickel prices
• OceanaGold says has not violated environmental regulations

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MANILA, Sept 27 (Reuters) - The Philippines has ordered the suspension of 20 more mines for environmental violations, most of them nickel producers, a government official said on Tuesday.

Worries of tighter supply from the world's top nickel ore exporter - where 10 mines have already been shuttered as part of an audit launched on July 8 and completed last month - helped global prices of the metal CMNI3 recover from the day's lows.

If those recommended for suspension are eventually halted, it would bring to 30 the total number of mines closed in the Southeast Asian nation, 18 of them nickel producers that account for more than half of the country's total nickel ore output based on last year's production.

Each miner that was ordered suspended "will be given a report and then they will have to explain their violations", Environment and Natural Resources Undersecretary Leo Jasareno told a news briefing.

"Immediately after this, we will be providing them with the reports (of the audit) with the instruction to explain why they committed the violations, within seven days from receipt of the reports," Jasareno later told reporters.

The threat of more mines being closed underpinned nickel prices on the London Metal Exchange (LME) CMNI3 . The metal was down 1.1 percent at $10,425 a tonne by 0548 GMT, after falling as much as 2.8 percent earlier.

Among those ordered suspended are OceanaGold Corp (OGC) , the top gold producer in the Philippines. Shares of the Australia-listed miner fell 8.2 percent on the news, prompting the firm to request for a trading halt pending an announcement.

"There have been no environmental violations by OceanaGold," OceanaGold CEO Mick Wilkes said in response to a Reuters email. Wilkes said the company will issue a statement in the next few hours.

The crackdown on the Philippines' mining sector has been led by Environment and Natural Resources Secretary Regina Lopez, an environmentalist who thinks open-pit mining is "madness".

"I have no beef with the mining industry, I am not against mining but I am definitely against the adverse effects that may happen, that are happening in some of the situations," Lopez said at the Tuesday briefing.