ISLAMABAD — Afghanistan’s Taliban said Sunday they had suspended “mediation” with the United States to exchange captive Sgt. Bowe Bergdahl for five senior Taliban prisoners held at Guantanamo Bay, halting – at least temporarily – what was considered the best chance yet of securing the 27-year-old soldier’s freedom since his capture in 2009.

In a terse Pashto language statement, Taliban spokesman Zabihullah Mujahid blamed the “current complex political situation in the country” for the suspension.

A U.S. official with knowledge of the talks said the cause of the suspension was not the result of any issue between the United States and the Taliban. He declined to elaborate.

Bergdahl, of Hailey, Idaho, was last seen in a video released in December, footage seen as “proof of life” demanded by the United States. Bergdahl is believed to be held in the border regions between Afghanistan and Pakistan.

Mujahid said the indirect talks with the United States had been mediated by Qatar, where the Taliban established a political office last June.

The video of Bergdahl was part of the negotiations which were to lead to the eventual transfer of the five Taliban leaders held since 2002 in Guantanamo Bay.

Mujahed did not elaborate on what “political situation” in Afghanistan led to the suspension of talks or say when they might resume. Afghanistan is in the middle of a presidential campaign ahead of an April 5 election.

Two-term President Hamid Karzai cannot run again for office under the Afghan constitution.