The Obama administration soon plans to issue new guidelines aimed at giving the hundreds of prisoners at an American detention centre in Afghanistan significantly more ability to challenge their custody, Pentagon officials say.

The new Pentagon guidelines would assign a US military official to each of the roughly 600 detainees at the American-run prison at the Bagram Air Base north of Kabul. These officials would not be lawyers but could for the first time gather witnesses and evidence, including classified material, on behalf of the detainees to challenge their detention in proceedings before a military-appointed review board.

Some of the detainees have already been held at Bagram for as long as six years. And unlike the prisoners at the Guantánamo Bay naval base in Cuba, these detainees have had no access to lawyers and no right to hear the allegations against them. The changes are expected to be announced this week after an obligatory Congressional review.