Chandigarh, June 15 : Avtar Singh Khanda, a Punjab-origin Khalistani separatist and mastermind of the attack on the Indian High Commission in London, died in a hospital in the UK on Thursday due to blood cancer. He was the head of Khalistan Liberation Force. A bomb expert, Khanda, who was the principal orchestrator of the March 19 violence at the Indian High Commission in London, was handler of arrested Waris Punjab De chief Amritpal Singh. Confirming the death, UK-based Khalsa Aid founder Ravi Singh has put a post on Instagram. Khanda, who belongs to Punjab's Moga town, was arrested by British authorities in March in connection with vandalisation with his supporters to protest crackdown on Amritpal. On Wednesday, the National Investigation Agency (NIA) had put out a series of photos on Twitter a "request for identification/information" of individuals who were "involved" in the attack on the High Commission. One of the individuals in the NIA photos were Khanda. "They caused grievous injuries to an official and disrespected the Indian National Flag," the NIA post said. /IANS