The office that acts as a watchdog of the U.S. Environmental Protection Agency is looking at the agency's handling of a report on the potential impacts of large-scale mining in Alaska's Bristol Bay region.

A spokeswoman with the inspector general's office said Tuesday the audit was prompted by congressional requests and hotline complaints.

The state of Alaska and the owner of the proposed Pebble Mine, Northern Dynasty Minerals Ltd., requested the investigate the EPA's preparation of the Bristol Bay watershed assessment. Both have raised concerns about potential bias within the EPA.

An EPA official said the agency plans to cooperate with the review.

The agency started a process under which it could restrict or prohibit development of the mine after concluding that large-scale mining in the Bristol Bay watershed posed significant risks to salmon.