Opponents of a railroad that would open Montana's coal fields to new mining want federal officials to halt their review of the proposal.

They allege the project is much larger than disclosed and would have impacts all the way to the West Coast.

Backers of the Tongue River Railroad say it would haul up to 20 million tons annually from a planned Arch Coal, Inc. mine near the Northern Cheyenne Indian Reservation.

But opponents want to turn the spotlight on the potential for the railroad to spur more mining of coal for export to Asia through Washington state. That could trigger a broader review of the $416 million line.

The Rocker Six Cattle Co. and Northern Plains Resource Council this week petitioned the government to reject the railroad's application.