The U.S. secretary of state is once again urging India to help Canada advance its investigation into the killing of Hardeep Singh Nijjar.

Antony Blinken says it's very important for India to co-operate so that the investigation can continue to move forward.

Blinken made the comments today after meetings with Prime Minister Narendra Modi and other senior Indian officials in New Delhi.

He says India and Canada are two close friends and partners of the U.S. and wants to see the dispute resolved as soon as possible.

Nijjar, a Canadian Sikh activist long denounced by India as an extremist, was shot and killed in June outside a gurdwara in Surrey, B.C.

In September, Prime Minister Justin Trudeau shocked the House of Commons with what he called "credible allegations" that agents of India's government were involved.

"These are two of our closest friends and partners, and of course we want to see them resolving any differences or disputes that they have as a friend of both," Blinken said.

"We think it's very important that India work with Canada on its investigation, and that they find a way to resolve this difference in a co-operative way. But that really does go with Canada moving its investigation forward and India working with Canada on it."