WASHINGTON, July 12 (Reuters) - U.S. Attorney General Eric Holder is considering whether to appoint a criminal prosecutor to investigate the Bush administration's interrogation practices involving the CIA, and is expected to make a decision in a few weeks, a Justice Department official said on Sunday.

The official, who declined to be identified, said any investigation would only cover those who went beyond the Justice Department's legal advice at the time that authorized various harsh interrogation techniques.

Those CIA employees who acted in accordance with the Justice Department's approved methods at the time would not be investigated, the source said on condition of anonymity.

This was the position the Obama administration announced in April when it released the Justice Department memos during the Bush era that had authorized waterboarding and other coercive methods of interrogation of terrorism suspects.

The official described Holder as "very reluctant" to open the investigation, but said the attorney general could be forced to do it because of the "nature of the conduct" at issue.

Justice Department spokesman Matthew Miller said Holder will "follow the facts and the law."

"We have made no decisions on investigations or prosecutions, including whether to appoint a prosecutor to conduct further inquiry," Miller said. "As the attorney general has made clear, it would be unfair to prosecute any official who acted in good faith based on legal guidance from the Justice Department."