Newfoundland and Labrador Premier Danny Williams is undergoing heart surgery later this week in the United States, in an apparent snub of Canadian health care.

Sources told the Globe and Mail late Monday that the premier is heading to an undisclosed location in the U.S., but gave no other details.

Earlier in the day, a spokesperson for Williams would only tell NTV News that the premier had left the province.

Deputy premier Kathy Dunderdale is expected to hold a news conference on the matter Tuesday morning.

Reports say Williams, a 59-year-old father of four, has shown no outward signs of illness. Friends say he had been playing hockey on a regular basis until recently.

Last Friday, he appeared before reporters alongside Prime Minister Stephen Harper.

With files from The Canadian Press