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, the first such probe of a sitting prime minister.

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.

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.