Bergdahl: I Was Chained And Beaten With Cable

US Army Sgt Bowe Bergdahl has detailed the torture he says he suffered during five years of Taliban captivity.

In a two-page letter, which his lawyer hoped might help spare him a court martial, Bergdahl, 28, said he was threatened with execution after trying about a dozen times to escape.

"In the beginning of my captivity, after my first two escape attempts, for about three months I was chained to a bed spread-eagle and blindfolded," Bergdahl wrote in the letter sent by his lawyer to military investigators on 2 March.

"Around my ankles where the chains were, I developed open wounds ... During these months some of the things they did was beat the bottoms of my feet and parts of my body with a copper cable."

The US Army announced on Wednesday the Idaho native had been charged with desertion and misbehaviour before the enemy .

Bergdahl, who left his remote outpost in Afghanistan's Paktika province in June 2009, could face up to life in prison if convicted on both charges.

He also said he was beaten with a rubber hose, punched and struck so hard with the butt of an AK-47 that its stock snapped off.

Bergdahl also said he was "kept in constant isolation" for the whole five years, much of the time in a small cage in dark rooms, chained to a heavy object.

His lawyer, Eugene Fidell, said his client's ordeal should be taken into account by investigators.

"This is a hellish environment he was kept in for nearly five years," he told the AP news agency, "particularly after he did his duty in trying to escape".

A high-ranking officer is to decide if there is enough evidence to bring the case to a court martial.

Meanwhile, the Obama administration has defended the deal under which Bergdahl was freed in May last year in exchange for the release of five Taliban detainees from Guantanamo Bay.

State Department spokeswoman Jen Psaki told Fox News on Wednesday the swap was "absolutely" worth it.