Amnesty International calls for the immediate and unconditional release of human rights defender Muhammad Hayat Khan Preghal, a prisoner of conscience who has been detained solely for peacefully exercising his right to freedom of expression. Muhammad Hayat Khan Preghal has been charged for comments he made online that were critical of Pakistani state policies. The detention marks the latest in a series of alarming attacks on human rights defenders – including activists, journalists, bloggers and users of social media.