Bosnia's most senior Muslim leader, Grand Mufti Husein Kavazovic on Friday urged the Islamic State to liberate a British hostage threatened with beheading by the jihadists. "Bearing in mind that the human life is sacred for Muslims, I call those who hold in detention David Haines to give up their threats and unconditionally leave this man to return to his family," Kavazovic said in a statement. Haines, taken hostage in Syria in March 2013, was threatened with death by IS militants during a video depicting the beheading of US journalist Steven Sotloff. The militant jihadist group said the journalist's killing, which came on the heels of its beheading last month of a**ther US reporter, James Foley, was in retaliation for expanded US air strikes against its fighters in Iraq.