Prime Minister Justin Trudeau's vacation to the Aga Khan's private island in the Bahamas cost taxpayers more than the government revealed to Parliament, CBC News has learned.

In addition to the initial $127,187 disclosed in documents tabled in the House of Commons, the government spent $6,695 to transport a Privy Council Office technician from Nassau to Bell Island by seaplane along with 400 pounds of equipment.

That brings the total cost to taxpayers as a result of Trudeau's vacation to the exclusive island to $133,883.

The revelation also raises questions about Trudeau's explanation for why he travelled from Nassau to Bell Island aboard the Aga Khan's private helicopter.

Conflict of Interest and Ethics Commissioner Mary Dawson is conducting an investigation following complaints about the trip and allegations that Trudeau violated government rules, which prohibit the prime minister, cabinet ministers and parliamentary secretaries from accepting free travel on non-commercial chartered or private aircraft without prior approval from the ethics commissioner.

As prime minister, Trudeau is also restricted for security reasons to travelling on government of Canada aircraft — even when on vacation.

Trudeau has defended the decision to hop aboard the Aga Khan's helicopter, insisting it was the only way to get to Bell Island.

"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 told reporters in Kingston, Ont., on Jan. 12.

"The fact is, as I have said many times, the Aga Khan is a personal family friend and travel to and from the island only happens through private means," he later added.

This seaplane ferried a Privy Council technician from Nassau to the Aga Khan's private Bell Island. (Bahamasrentalvacations.com)

The technician, however, made the same trip from Nassau to Bell Island aboard a commercially chartered Cessna 208 seaplane. The nine-seat aircraft, which has flown to Bell Island on other occasions, takes about 30 minutes to ferry passengers from Nassau to the island.

Trudeau has come under fire in the House of Commons for the trip and for his office's initial refusal to disclose where he was vacationing.

Liberal MP and longtime friend Seamus O'Regan and his husband, Steve Doussis, joined Trudeau's family on the island along with Liberal Party president Anna Gainey and her husband, Tom Pitfield, a key member of Trudeau's election campaign team.

In January, O'Regan told the National Post that he and his husband also travelled on the Aga Khan's helicopter. As an MP, O'Regan is not bound by the same rules as the prime minister and cabinet ministers.

Liberal MP Seamus O'Regan and his husband vacationed on the Aga Khan's island with Trudeau. (CBC)

Trudeau has defended the trip, arguing that the Aga Khan — a billionaire and leader of the world's Ismaili Muslims — is a longtime family friend.

However, the Aga Khan Foundation Canada, which lists the Aga Khan as its chairman in its most recent filings with the Canada Revenue Agency's charities section, has received federal government grants in the past for its international development projects. It is currently registered to lobby several government offices, including the prime minister's office.

Any time a prime minister goes anywhere, even on vacation, it costs the government money.

In addition to the RCMP security detail that accompanies the prime minister, the Privy Council Office provides a technician, who supplies technical support and ensures that the prime minister has access to a secure office and secure communications.

In this case, the technician was originally scheduled to travel to the island via Flamingo Air. Flamingo Air generally lands on a nearby island and people take a boat to Bell Island from there.

Instead, the decision was made to charter a seaplane for the 115 km flight with Land and Sea Charters of Nassau.

The Aga Khan's privately owned Bell Island is located in the Bahamas. (Google Maps)

"The reason for the charter was in order to be able to ship 400 pounds of equipment for the PM's security detail and to set up a temporary secure office to maintain a communications link for the prime minister with Ottawa," said Privy Council spokesman Raymond Rivet.

"This type of support is required in all circumstances to support the PM and this is also in line with the cost of past shipments for previous prime ministers."

While the government had to reimburse the technician $300 for the Flamingo Air flight that wasn't taken, the move saved the cost of having a diplomatic courier from Global Affairs accompany the equipment to Bell Island, Rivet explained.

Previously, the Privy Council Office has revealed that $1,604, listed as per diems in the documents tabled in the House of Commons, was paid to the island's owner to cover room and board for the technician.

Trudeau has reimbursed the government $4,895 for the Department of National Defence flight to Nassau for his family and nanny Marian Pueyo on Dec. 26. DND has estimated the Challenger CC-144 flight cost $32,000 in flying time and $1,720 in food, beverages and associated fees.

While Privy Council and Global Affairs have answered questions from CBC News about their costs in relation to the Bahamas vacation, the RCMP has steadfastly refused to provide any breakdown of how it spent $53,253 in "travel, accommodation and per diems," saying it would jeopardize the prime minister's security.

Elizabeth Thompson can be reached at elizabeth.thompson@cbc.ca