The government is "ascertaining" details as to how convicted Khalistani terrorist Jaspal Atwal got a visa to enter India, External Affairs Ministry spokesperson Raveesh Kumar today said.\u00a0A controversy erupted after Canadian High Commissioner Nadir Patel invited Atwal for a dinner which he was hosting for the visiting Canadian Prime Minister Justin Trudeau and his delegation tonight. The high commission later said the invitation to Atwal was cancelled. "There are two aspects of this. One is his presence at the event. I think this is something which should be addressed by the Canadian side. They have said that it was an oversight. And that is the reason the invitation for the reception tonight has been withdrawn. "On the visa part, I cannot immediately say how that happened. There are different ways of people coming into India, whether you are an Indian national, or OCI card holder. We are ascertaining details from our mission. We will have to see how this happened," Kumar told reporters. Atwal was convicted for trying to kill the then Punjab minister Malkiat Singh Sidhu in Vancouver in 1986. The cancellation of the invitation comes at a time when Trudeau's pro-Khalistan approach is being criticised by many including Punjab Chief Minister Amarinder Singh, who raised the issue with the Canadian prime minister during a meeting. On his part, Trudeau assured Singh that his country does not support separatism in India or elsewhere.