(Reuters) - An investigation into the circumstances surrounding the capture of Army Sergeant Bowe Bergdahl by Taliban militants in Afghanistan has been completed, but it is unclear when the military will finish its report, the Pentagon said on Tuesday.

Pentagon spokesman Army Colonel Steve Warren said Major General Kenneth Dahl had submitted his initial report to the military chain of command for review. Warren said there was no way of telling when the review process would be completed.

The Pentagon appointed Dahl to investigate the case, determine if Bergdahl had broken military rules and recommend punishment if appropriate.

"The investigating officer has done his work but now that work is moving through the Army system, and at each stop ... there will ... be questions, requirements for clarification," Warren told reporters. "So it's working its way through the system as would any other investigation."

Warren rejected news reports suggesting that results of the investigation were being delayed until after the November elections to avoid re-igniting the controversy surrounding the prisoner swap that led to Bergdahl's release.

The Government Accountability Office, a government watchdog agency, said in August that the Defense Department had violated U.S. law by failing to alert Congress before releasing five Taliban members held at Guantanamo Bay military prison in Cuba in exchange for Bergdahl.

Bergdahl was released in May after five years in captivity.

Some of his fellow soldiers in Afghanistan have said that Bergdahl was captured by the Taliban after he deserted his post.

President Barack Obama's administration was initially praised for securing his release, but there was backlash from critics who charged that the White House had failed to give Congress adequate notice before freeing prisoners from Guantanamo.