BHP says Australia nickel mine hit by 2nd rockfall

SYDNEY, July 2 (Reuters) - For the second time in less than a month BHP Billiton Ltd (BHP.AX)(BLT.L) has temporarily closed its Perseverance nickel mine in west Australia due to rock falls around the site, the company said on Thursday.

The underground mine remains partially closed in the area affected by the incident, which occurred late on Monday, though mining resumed in other sections of the mine the next day, according to a BHP spokeswoman.

Authorities have ordered BHP Billiton to commission an independent assessment to demonstrate whether mining was safe before resuming full operations, the company said, adding it was confident it could do so.

BHP Billiton was forced to suspend mining temporarily on June 10 when a rock fall trapped a mine worker about 1,000 metres (3,281 feet) underground and had not yet returned to full operations before the second incident occurred.

The worker was uninjured in the incident and rescued about 16 hours later.

Perseverance is part of the company's Nickel West complex in west Australia. Nickel West produced about 27,000 tonnes of nickel in the March quarter. (Reporting by James Regan)