Hague wrote to Shaker Aamer to assure him the government was still trying to reunite him with his family in Britain as Aamer's health has deteriorated.
"Shaker was absolutely thrilled with the letter from Hague," Clive Stafford Smith, director of the rights group Reprieve. told the British newspaper the Observer. "It shows how a certain amount of personal commitment by someone in power can help someone who has been downtrodden in such a ghastly way."
Stafford Smith said Aamer, who has been in prison for 11 years, was involved in a hunger strike, which he said was spreading among inmates. The result has been a drastic deterioration of his health.
Aamer, 44, was captured in Afghanistan by U.S. troops in 2002. He has not been formally charged with any crimes; however, he reputedly led a unit of military fighters and had ties to top-tier al-Qaida leaders over the years.