India's top court on Friday ordered an investigation into use of "excessive and retaliatory" force by security forces in the insurgency-wracked state of Manipur, where a controversial law gives troops powers to shoot on sight. The Supreme Court was responding to petitions demanding that the government investigate the 1,528 extrajudicial killings alleged to have been carried out by the army, police and paramilitary forces in the northeastern state between 2000 and 2012. Rights campaigners say security forces are acting with impunity because of the controversial Armed Forces Special Powers Act (AFSPA) in force in Manipur, which is home to a number of armed separatist groups. The act, which covers large parts of northeastern India as well as Kashmir, gives Indian forces sweeping powers to search, enter property and shoot on sight, and is seen by critics as a cover for human rights abuses. The court asked the central and state governments and National Human Rights Commission, an independent body, to compile a report on so-called "fake encounters." The term is used to describe staged confrontations in which police or military forces execute unarmed suspects and later claim it as self-defense. "According to the police and security forces, the encounters are genuine and the victims were militants or terrorists or insurgents killed in counter insurgency or anti terrorist operations. Whether the allegations are completely or partially true or are entirely rubbish and whether the encounter is genuine or not is yet to be determined, but in any case there is a need to know the truth," a bench of Supreme Court justices said in response to the petition. The state government says security forces need the powers to help them battle multiple rebel groups whose long-standing demands range from secession to greater autonomy and land rights. But human rights groups say it provides cover for soldiers who cannot be prosecuted unless the national government gives its sanction. Activist Irom Sharmila has been on a 15-year-long hunger strike against the AFSPA in Manipur and has spent years in judicial custody, where she is force-fed via a drip. She began her campaign in November 2000 after witnessing the killing of 10 people by the army at a bus stop near her home in Manipur. The Supreme Court said it would decide in the next four weeks how the investigation should be conducted.