By Jessica Donati and Hamid Shalizi KABUL (Reuters) - The United States wants Afghanistan to halt the release of 88 prisoners from an Afghan jail because they pose a serious threat to security, U.S. officials said on Wednesday, adding to strains between the two sides. The United States only recently transferred the prison at Bagram to Afghan control after it had become a serious source of tension with the government in Afghanistan which is fighting a Taliban-led insurgency. Relations with Afghanistan have grown particularly strained over President Hamid Karzai's refusal to sign a bilateral security deal that would keep around 8,000 U.S. troops in the country after 2014, when most foreign forces are due to leave. "The Afghan Review Board has exceeded its mandate and ordered the release of a number of dangerous individuals who are legitimate threats and for whom there is strong evidence supporting prosecution or further investigation," said Colonel Dave Lapan, a spokesman for U.S. forces in Afghanistan.