London, Oct 3 : The family of Avtar Singh Khanda -- the principal orchestrator of the violence at the Indian High Commission in London who died this year -- has sought a formal inquest into his death from the chief coroner for England and Wales. The request by the family, as well as the Sikh Federation UK, came just as Khalistan supporters staged an anti-India protest outside the Indian High Commission in London on Monday. It also corresponds with a bitter diplomatic spat between New Delhi and Ottawa, fuelled by Canadian Prime Minister Justin Trudeau's recent allegations of India's involvement in the death of pro-Khalistan hardliner Hardeep Singh Nijjar. Both Nijjar and Khanda were associated with Khalistani organisations banned as terror groups in India. According to the Guardian, the call for an inquest is being led by the barrister Michael Polak, who alleged that the British police should have understood that Khanda was potentially in danger. Polak said he could not definitively state that India was behind Khanda's death, but that the circumstances clearly called for an investigation. 'If it was happening in a vacuum and we believed India was a law-abiding country, we would say that it is unlucky. But there were threats against him and he was named as enemy No 1 (in the media). At the very least it is suspicious,' Polak told the Guardian. Khanda died on June 15 this year after he was admitted to a hospital in Birmingham due to sudden illness. The official cause of death, which was declared post-mortem, was acute myeloid leukaemia (blood cancer). His family said they have not received medical records, nor evidence that backed the leukaemia diagnosis. His mother, who was not able to attend the funeral after allegedly being denied a visa by the Home Office, said she believed he was poisoned, the news report stated. The West Midlands police said they had undertaken a 'thorough review' of Khanda's death and that they had concluded there were 'no suspicious circumstances'. Khanda was also the handler of arrested Waris Punjab De chief Amritpal Singh, and played a key role in establishing him after the death of Deep Sidhu, IANS had reported earlier. Amritpal was arrested by the Punjab police on March 23 and charged with crimes relating to disharmony among classes, attempt to murder, attack on police personnel, etc. /IANS