Britain said on Wednesday India's cooperation with Canada's legal process was "the right next step" in the ongoing diplomatic row between the two countries, adding that it had full confidence in Canada's judicial system.

Canada on Monday linked India's high commissioner and other diplomats to the murder of Sikh leader Hardeep Singh Nijjar on its soil and accused New Delhi of a broader effort to target Indian dissidents in Canada.

India, which has long denied the accusations, retaliated by ordering the expulsion of six high-ranking Canadian diplomats including the acting high commissioner.

"We are in contact with our Canadian partners about the serious developments outlined in the independent investigations in Canada. The UK has full confidence in Canada’s judicial system," the British government said in a statement.

"The Government of India's cooperation with Canada's legal process is the right next step."