WASHINGTON — The U.S. Labor Department on Wednesday refused to let the Utah Mine Safety Commission have any information from the Crandall Canyon Mine accident investigation until the inquiry is over, citing "grave concerns" that the panel's involvement would jeopardize the department's work.

Commission Chairman Scott Matheson Jr. had asked the Mine Safety and Health Administration for full cooperation as the government conducts its investigation into the accident last month. The accident trapped six miners where rescuers were killed and six were injured. Matheson has said the commission is not there to investigate the accident but wants access to information.

However, in a letter sent Wednesday to Matheson, Jonathan Snare, the Labor Department's acting solicitor, asked the commission "to respect our very real need to preserve the integrity of our law enforcement investigation."

"By granting the commission members, including a member of the trade association that includes the Crandall Canyon mine owners, access to sensitive investigative information during the progress of the investigation, we run an unacceptable risk that testimony of witnesses could be prejudiced, witnesses could be intimidated and possible civil or criminal violators could be tipped off that they are under suspicion," Snare wrote. "I am sure you can appreciate the impropriety of giving the public access to such information during a law enforcement investigation."

Snare said the department will cooperate with the commission but "respectfully requests that you defer on your request for interviews and documents generated by the accident investigators given the obvious need for confidentially for a law enforcement investigation."

Contacted by the Deseret Morning News Wednesday, Matheson said he had not received the letter yet and wants to read it before he comments.

The Labor Department took issue specifically that the Utah Mining Association is part of the commission and it represents owners of the Crandall Canyon Mine.

"This composition of stakeholders is highly appropriate for the purposes of reviewing the roles of the federal, state and local governments and private industry in the area of mine safety and for recommending reforms, but not for creating an investigative record that must stand up to judicial scrutiny," Snare wrote.