This undated image provided by the US Army shows Sgt. Bowe Bergdahl. [Photo/icpress.cn]

WASHINGTON - A new video has surfaced showing Bowe Bergdahl, a US soldier captured by militants while stationed in Afghanistan more than four years ago, the soldier's family said on Wednesday.

"Today we learned that a new video of our son, US Army Sgt. Bowe Bergdahl, has been distributed by his captors," Bergdahl's family said in a statement relayed by the Idaho National Guard.

"As we have done so many times over the past four and a half years, we request his captors to release him safely so that our only son can be reunited with his mother and father," Bergdahl's family said.

Bergdahl was stationed in Paktika province in eastern Afghanistan when he disappeared under unclear circumstances on June 30, 2009, about two months after arriving in Afghanistan.

He is believed to be held by Taliban-linked militants in Pakistan.

US efforts to free Bergdahl, the only US soldier from the Afghan war known to be held by militants, have so far been unsuccessful.

US officials said Bergdahl appeared to be in 'declining health,' but not gravely ill, in the video, which US officials believe was recorded within the last month. The video came to the US officials' attention in the last few days.

It was not immediately clear how it was obtained or viewed.

"Sgt. Bowe Bergdahl has been gone far too long, and we continue to call for and work toward his safe and immediate release," said Elissa Smith, a Pentagon spokeswoman.

Smith said the United States was using "military, intelligence and diplomatic tools" to ensure Bergdahl would return safely.

Bergdahl's family addressed the soldier directly in their statement.

"BOWE - If you see this, continue to remain strong through patience," they said. "Your endurance will carry you to the finish line. Breathe!"