Canada’s Senate speaker will not attend a two-day G20 event in New Delhi this week, India said on Thursday, as ties remain frozen after Canada said it is investigating allegations linking Indian agents to the killing of a Sikh separatist leader.

Speaker Raymonde Gagne will not be present at the two-day parliamentary speakers’ summit that starts on Friday, as part of India’s year long presidency of the Group of 20 (G20) major economies, which expires in November.

“We invite all members for G20 events. Participation is their decision and subject to a number of factors,” said Indian foreign ministry spokesperson Arindam Bagchi.

“I’ll have to check whether anybody is actually attending from Canada because the parliament speaker could not attend.”

The Canadian senate did not immediately respond to a request for comment from Reuters.

Indian media cited India’s lower house speaker as saying Canada would be represented by the Senate speaker.

Tensions between India and Canada have escalated after Canadian Prime Minister Justin Trudeau publicly levelled suspicions last month that New Delhi’s agents were involved in the murder of Hardeep Singh Nijjar, who was shot dead by unidentified gunmen on June 18 in a Vancouver suburb.

India dismissed the allegation as absurd and both countries expelled a diplomat. India also suspended issuing new visas for Canadians and asked Ottawa to reduce its diplomatic presence in India.

Bagchi said that India is in touch with Canada at “various levels” and remained “committed to ensuring parity” on Canadian diplomatic presence.