Canadian officials on Thursday admitted that a Sikh militant convicted of attempting to murder an Indian minister had been invited to dinner with Prime Minister Justin Trudeau in New Delhi, in the latest controversy to dog the premier's week-long visit to India.

A statement confirming Jaspal Atwal's invitation to Thursday's official event had been cancelled comes less than a day after Trudeau sought to quash perceptions his administration was soft on Sikhs seeking an independent state.

The Canadian embassy told AFP it “has rescinded Mr. Atwal's invitation”.

Atwal was convicted for a botched assassination attempt on an Indian minister in Canada in 1986, and was sentenced to 20 years by a Canadian court.

He reportedly attended an event in Mumbai on Tuesday, where he was photographed alongside Trudeau's wife Sophie Gregoire, according to Canada's public broadcaster CBC.

The embassy would not comment on whether Atwal was part of Trudeau's official delegation, although reports in Canada said Trudeau's office had denied this.

“We do not comment on matters relating to the PM's security,” it said.

Atwal was a member of the International Sikh Youth Federation, an organisation outlawed in India and Canada, among other places, that seeks an independent Sikh state of Khalistan.

India's foreign ministry said it was investigating how Atwal -- a Canadian passport holder of Indian origin -- managed to obtain a visa to travel to India.

“We are trying to find out, and ascertain details from our mission (in Canada),” ministry spokesman Raveesh Kumar told reporters in New Delhi.

Canada is home to roughly half a million Sikhs and Trudeau's administration has been accused of being too cosy with those agitating for a separate homeland in India's northern Punjab state.

Trudeau particularly riled New Delhi last year when he attended a parade in Canada at which Sikh militants were feted as heroes.

Tensions over the Khalistan issue have marred Trudeau's visit, and fuelled speculation the prime minister was being snubbed by his Indian counterpart Narendra Modi.

Modi has been notably absent since Trudeau and his family arrived Saturday evening.

Government officials greeted the Trudeaus at the Taj Mahal and in Modi's home state of Gujarat, where Israeli Prime Minister Benjamin Netanyahu was last month personally escorted by the Indian leader.

Trudeau on Wednesday sought to dispel perceptions his administration was too close to Sikh separatists, telling Punjab's chief minister Canada did not sympathise with extremist movements.

But photographs of Atwal flanked by Canadian officials at the Mumbai event attended by Trudeau have thrust the controversy back into the headlines.

Modi and Trudeau are scheduled to meet on Friday in New Delhi at the tail end of his first visit as prime minister to India.