BHP Billiton’s Leinster nickel operation in Western Australia has been closed after a rockfall on 29 June trapped a mine worker underground.

A seismic event caused a minor fall of ground in the Perseverance underground mine, BHP Billiton said in a statement.

The mine had recently reopened after a rockfall on 10 June.

The trapped worker walked out of the mine once a risk assessment had been completed in the early hours of 30 June, WA Today reported.

Australian Manufacturing Workers’ Union (AMWU) state secretary Steve McCartney said the incident highlighted the safety issues at BHP mines.

Five workers have died at BHP iron ore sites in Pilbara during the last ten months.

McCartney said the AMWU will demand a federal parliamentary inquiry, according to a report on