The number of detainees on a hunger strike at the U.S. prison in Guantanamo Bay (search) has fallen by almost two-thirds since last week, a military official said Tuesday.

Forty-five detainees are currently on the hunger strike, down from 131 last week, Guantanamo spokeswoman Lt. Angela King Sweigart said in an e-mail message. Detainees must miss nine straight meals for the military to classify them as being on a hunger strike (search).

On Thursday, the military said the hunger strike had grown to include 131 detainees — more than a quarter of the base's some 500 prisoners — the largest number since the protest began Aug. 8.

King-Sweigart did not say whether any detainees had missed fewer than nine consecutive meals since last week.

No explanation was given for the sharp decrease, and calls to military officials at Guantanamo went unanswered Tuesday evening.

Fifteen of the 45 detainees on the hunger strike have been hospitalized, King-Sweigart said. She could not immediately say if any were being tube fed.

Several detainees have been tube fed during the hunger strike, either through their noses or intravenously.

The New York-based Center for Constitutional Rights, which has filed legal challenges on behalf of detainees, has claimed that 210 detainees are participating in the hunger strike.

The detainees are accused of ties to the Al Qaeda (search) terror network or Afghanistan's ousted Taliban (search) regime.