An oil company says 420 to 630 gallons of crude leaked from a flow line at its field in northwestern Montana for up two weeks before the spill was discovered.

The leak at the FX Energy Inc. oil field east of Cut Bank is the second significant oil spill in Montana this month. The amount, 10 to 15 barrels, appears to be much less than the estimated 1,000 barrels that emptied into the Yellowstone River when an Exxon Mobil Corp. pipeline broke.

An FX Energy vice president says it's unclear when the line broke, but he estimates the leak lasted between 10 and 14 days before it was discovered last Tuesday.

The spill is on the Blackfeet Indian Reservation. The tribe has hired a response team to clean it up.

Associated Press