OTTAWA, Jan 16 (Reuters) - Canada's ethics watchdog is investigating whether Prime Minister Justin Trudeau violated conflict of interest laws by taking a New Year's vacation on an island in the Bahamas owned by the Aga Khan.

Trudeau has faced repeated questions from the opposition about his trip to Bell Island, the Aga Khan's private island, which sits in a national park in the Bahamas. He said last week that he had flown there by private helicopter. urn:newsml:reuters.com:*:nL1N1F2252

Aga Khan is the title held by the leader of the Ismaili branch of Shi'ite Islam. The current Aga Khan, Prince Shah Karim Al Husseini, is a Trudeau family friend.

The Aga Khan Foundation Canada is a registered lobbyist with the government and executives met with government officials as recently as December.

In a letter to a Conservative lawmaker dated Jan. 13, Mary Dawson, the federal conflict of interest and ethics commissioner, said she has "commenced an examination" to determine whether Trudeau's trip contravened the Conflict of Interest Act.

In the letter, Dawson acknowledged concerns about potential breaches related to the use of the private helicopter, as well as Trudeau's acceptance of the trip in light of the Aga Khan Foundation's lobbying of the government.

The probe could be a blow to Trudeau, who has enjoyed high ratings even as the Liberals have been dogged by spending controversies, including his health minister's use of a luxury car service owned by a party supporter. urn:newsml:reuters.com:*:nL1N1B50WI

The last Liberal government, ousted in 2006, was tarnished by a sponsorship scandal involving corruption and misdirection of funds to supporters in Quebec.

In an apparent bid to reconnect with voters, Trudeau scrapped a trip to this week's World Economic Focum in Davos and embarked on a cross-country tour instead.

Official ethics rules introduced by Trudeau himself in 2015 bar government ministers from taking private flights without getting Dawson's approval.

A Trudeau spokesman declined to comment on whether an examination has been launched and said the prime minister will answer any of Dawson's questions. A spokeswoman for the ethics commissioner did not immediately comment.

Trudeau is facing a separate probe by Dawson into fundraising by his Liberal Party, but an examination into the trip would be the first such investigation of a prime minister, said Duff Conacher, co-founder of Democracy Watch.

(Reporting by Leah Schnurr; Editing by Paul Simao and Cynthia Osterman) ((leah.schnurr@thomsonreuters.com; +1 613 788 8203; Reuters Messaging: leah.schnurr.thomsonreuters.com@reuters.net; Twitter: @LeahSchnurr))