HELENA, Mont. -

A mining company is dropping its plans to dig a mile-long tunnel for a copper development project near the Smith River.

Department of Environmental Quality spokesman Chris Saeger said Monday Tintina Alaska Corp. sent the agency a letter withdrawing its exploration license request for the Big Butte Copper Project.

The DEQ previously approved the tunnel, which would produce a 10,000-ton bulk sample of rock for testing.

In March, two environmental groups filed a lawsuit challenging the DEQ's decision.

Jim Jensen of the Montana Environmental Information Center accuses Tintina of planning to use the exploration tunnel to conduct mining activities without taking the proper regulatory steps.

Jerry Zieg of Tintina says the company still intends to pursue an operating permit for a mine after gathering additional data from less-invasive exploratory drilling.