Summer fires have burned more than 41,000 acres of Plum Creek Timber lands in Montana, affecting supplies to the mills and curtailing production.

Similar fires in 2003 caused losses of US$4m, but company officials said the cost could not yet be fully determined. A salvage survey was expected to get under way next week and until then it was impossible to estimate the merchantable quality of some of the affected timber.

Fires burned across five areas. At some sites the fires forced Plum Creek to curtail shipments of logs to its mills, reducing the number of truckloads by around 250 a day and causing some shutdowns.