CHEYENNE, Wyo. — U.S. officials said Thursday that they misspoke when they recently announced they had approved an expansion of a Montana coal mine that would keep it operating for another 19 years.

U.S. Interior Department spokeswoman Heather Swift said the 60-million-ton mine expansion is under review. In an email, she blamed “internal miscommunication” for the incorrect announcement last Friday about Westmoreland Coal Company’s Rosebud Mine.

Officials with Englewood, Colorado-based Westmoreland didn’t immediately respond to a request for comment Thursday. The company’s stock price jumped 11 percent Tuesday after Friday’s inaccurate statement from the Interior Department.

Westmoreland has seen its stock price plummet over the past year, from more than $18 per share to a little over $1, prompting speculation it could follow other coal producers into bankruptcy. It settled at $1.30 at closing Thursday.

The Interior Department merely plans to release a draft study of the expansion for 45 days of public review and comment, Swift said Thursday by email. She wasn’t sure when the public comment period would occur.

Most coal mined in the U.S. West belongs to the federal government. The planned study is part of a government process that typically takes several years and culminates with the coal being offered at auction. The auctions rarely draw more than one bidder besides the owner of the mine adjacent to the coal.

Sometimes, though, a competing company submits the highest bid. Occasionally, the U.S. Bureau of Land Management determines the bids are too low and doesn’t award the lease to anybody.

The Rosebud Mine supplies coal to the 2,100-megawatt power plant in Colstrip, Montana, one of the largest in the western U.S. The plant, owned predominantly by Puget Sound Energy, provides power to customers across the Pacific Northwest.

The expansion would add 10.5 square miles (27 square kilometers) to the 40-square-mile (104-square kilometer) strip mine and would help keep the mine operating after the power plant shuts down two of its four generating units in 2022 as planned.