About 200 miners from Helensburgh's Metropolitan Colliery have walked off the job for 48 hours after a breakdown in enterprise agreement negotiations with management.
CFMEU south-western district vice-president Bob Timbs said the stoppage followed three days of bans and limitations by workers after ongoing negotiations with Peabody Energy came to a halt.
"We've been in negotiations for a replacement enterprise agreement for the last six months, but we've come to an impasse," he said.
"So we have exercised our right to lawful industrial action. On Monday, we put some bans on the amount of production, on Tuesday we put a ban on the use of diesel-operated vehicles in the mine and on Wednesday, we put another ban on the amount of production.
"On Wednesday at 11pm, we started a 48-hour stoppage."
However, Mr Timbs said the union had yesterday agreed to provide a skeleton crew due to safety concerns.
"Unfortunately, the longwall is in some geologically unsound conditions. So, after a discussion with management [yesterday], we will supply a skeleton crew to operate the longwall to maintain stability and safety within the mine," he said.
Mr Timbs said the company's current pay offer fell short of workers' expectations.
"First, they offered zero per cent increase in pay over three years, then they made a counter-offer with minimal increases over years two and three," he said.
He said that would still put Helensburgh miners more than 20 per cent below the pay of other miners within the mining district.
Peabody Energy could not be reached for comment last night.