Solid Energy has had to stockpile coal at one of its mines because of storm damage to the rail line connecting the West Coast to the Port of Lyttelton.
KiwiRail says the line that takes coal from the Westport area to Greymouth was badly affected earlier this week and may not be open for another week.
Solid Energy, which relies on the route to move coal from its Stockton mine to Lyttelton, says the option of trucking the coal will not be considered until the rail situation is clearer.
It says in the meantime, there's enough room for it to stockpile coal near the mine.
The company says a ship is not due to pick up coal from Lyttelton until next month.