Prime Minister Justin Trudeau has confirmed he and his family accepted trips on the Aga Khan's private helicopter during his vacation to the spiritual leader's private island in the Bahamas, which appears to violate a section of the Conflict of Interest Act.

"The travel back-and-forth from Nassau to the island happens on the Aga Khan's private helicopter, which he offered us the use of," Trudeau said Thursday.

Trudeau said travel to Bell Island "only happens through private means."

Conflict of Interest and Ethics Commissioner Mary Dawson is considering an investigation into Trudeau's vacation, which took place after Christmas.

"It's something that certainly we look forward to discussing with … the conflict of interest and ethics commissioner. But we don't see an issue on that," Trudeau said.

Conservative MP Andrew Scheer wrote the ethics commissioner Monday asking for a review of whether the trip is a gift that violates the Conflict of Interest Act.

Section 12 of the act also has rules prohibiting cabinet ministers from accepting sponsored travel.

"No minister of the Crown, minister of state or parliamentary secretary, no member of his or her family and no ministerial adviser or ministerial staff shall accept travel on non-commercial chartered or private aircraft for any purpose unless required in his or her capacity as a public office holder or in exceptional circumstances or with the prior approval of the Commissioner."

PM Justin Trudeau says he did fly on the Aga Khan's private helicopter which the opposition claims may be a breach of the federal Conflict of Interest Act. 1:53

The Open and Accountable Government guidelines on the prime minister's website repeat the restriction on sponsored travel — providing leeway in "exceptional circumstances and only with the prior approval" of the ethics commissioner.

The prime minister said he did not go to the ethics commissioner before his trip.

NDP leader Tom Mulcair said in a statement that the prime minister has admitted to breaking the Conflict of Interest Act.

"These were not exceptional circumstances and therefore cannot excuse the use of a private helicopter," he said. "This is a clear conflict of interest and it's worrisome that the prime minister has been so evasive about the specifics of this trip."

PMO reluctant to provide details

​The Prime Minister's Office had been tight-lipped about Trudeau's vacation until the National Post reported last week that he was in the Bahamas and staying with the Aga Khan.

It has continued to be reluctant in releasing details of the trip.

On Wednesday, the PMO confirmed that Liberal MP Seamus O'Regan and his husband, Steve Doussis, as well as Liberal Party President Anna Gainey and her husband, Tom Pitfield, were guests on the family trip.

On Thursday, the Canadian Armed Forces said Trudeau has reimbursed the Crown $4,895.94 for personal use of the Challenger aircraft on Dec. 26, 2016 to fly to Nassau. This is standard for personal use of the government plane.

The reimbursement was to cover travel for Trudeau, his wife, Sophie Grégoire-Trudeau, their three children and nanny Nancy Peuyo.

Family friend and his foundation

Trudeau has described the Aga Khan as a longtime family friend he has known his whole life, who was also an honorary pallbearer at his father Pierre Trudeau's funeral.

Conservative MP Blaine Calkins raised the Aga Khan's relationship with Trudeau in a letter to the ethics commissioner Wednesday. He asked whether the relationship means the prime minister should recuse himself from government decisions related to the Aga Khan and his foundations' dealings with the government.

"[Trudeau's] official filings do not include an ethics screen regarding the Aga Khan or his Foundation. I would ask that you consider whether such a screen should be implemented and whether in the past year Mr. Trudeau has been involved in any business that would be in violation of Section 6 [of the Conflict of Interest Act," the letter said.

The Aga Khan's privately owned Bell Island is located in the Bahamas. The Trudeau family took the Challenger jet to Nassau, Bahamas prior to taking the Aga Khan's helicopter. (Google Maps)

Trudeau said he had not disclosed his relationship to the Aga Khan in his ethics filings but the relationship is "well known."

Prince Karim Aga Khan IV is the hereditary spiritual leader of the world's 15 million Shia Ismaili Muslims and a wealthy philanthropist.

He is head of the Aga Khan Development Network, which receives some of its funding from the Canadian government, to support social development, education and charity projects.

The relationship between Canada and the AKDN goes back decades and includes millions of dollars' worth of projects from both Liberal and Conservative governments.

The most recent grant was a five-year, $55-million project to improve health services in Afghanistan that was announced in December 2015 under the Trudeau government.