The New South Wales mining industry is warning a 48 hour strike by coal train drivers could damage the Hunter Valley's international reputation.
Around 800 Pacific National drivers walked off the job at midday today over failed pay negotiations between the company and the Rail, Tram and Bus union.
Pacific National says at least 600,000 tonnes of coal worth $50 million will not reach the Port of Newcastle, as well as Port Kembla, as a result.
The union says there are no plans to cause access problems on the Hunter rail line while workers are striking.
National secretary Bob Nanva says workers will try to ensure trains are stowed away from the main line so access is not an issue for other operators.
"We don't want to cause any inconvenience to third parties, to parties other than Pacific National," he said.
Mr Nanva says the industrial action was a last resort.
"This company has refused to bargain a fair and reasonable agreement," he said.
But the Minerals Council of New South Wales is warning the strike could have detrimental impacts for the Hunter Valley's economy.
CEO Stephen Galilee is hoping the dispute will be resolved as quickly as possible.
"To protect the reputation of the Hunter Valley coal supply chain, here in Australia but also overseas as well," he said.
Whitehaven Coal's operations will be halted because it only uses Pacific National for its coal haulage.
Xstrata Coal plans to reduce the strike's impact by using its own trains.
The Australian Rail Track Corporation says it is working with Pacific National and other service providers to find other options.
The Newcastle Coal Infrastructure Group says stockpiling is standard process in the industry and says it expects ship loading will continue as normal at its loading facilities.