Conservative leadership candidate Andrew Scheer says he's written to Ethics Commissioner Mary Dawson to request a probe into Prime Minister Justin Trudeau's vacation at a private island owned by the Aga Khan.

In a press release Monday, Scheer referred to Trudeau's stay on the island as a gift, and says he's asked Dawson to examine whether accepting the accommodation violated the Conflict of Interest Act.

Trudeau's office confirmed last Friday that he, his family and some friends stayed on Bell Island during their vacation in the Bahamas.

Bell Island is owned by the Aga Khan, the spiritual leader of the world's 15 million Ismaili Muslims. His Canadian foundation, the Aga Khan Foundation of Canada, receives tens of millions of dollars a year from the Canadian government for international development work.

A spokesman for Trudeau didn't respond last Friday, to a inquiry as to whether Trudeau cleared the holiday with Dawson before accepting it. He pointed out the Aga Khan is a long-time friend of the Trudeau family. The religious leader was an honorary pallbearer at the funeral of Trudeau's father, former prime minister Pierre Trudeau.

Scheer says he takes the rules for MPs very seriously.

"The prime minister of Canada must be held to the highest standard, which is why I have called for this investigation," Scheer said in the release.

A spokeswoman for the Aga Khan Foundation of Canada didn't respond Friday or Monday to a request for comment.

The Conflict of Interest Act bars public office holders like MPs from accepting gifts that might be seen to influence them, but allows several exceptions, including one for gifts from family and friends.

In an interview with Omar Sachedina on CTV's Power Play, Scheer said the problem is Trudeau accepted a gift from someone whose foundation receives Canadian tax dollars. He suggested the friend exemption may not apply in a case where a gift can be reasonably seen to be influencing decisions.

"I don't think anybody begrudges a vacation...[but] this is, it seems, the first time that he's accepted this kind of gift and that is what is so troubling," Scheer said.

"The Prime Minister's Office went to great lengths to keep this vacation secret."