The outgoing U.S ambassador to Canada is warning the next administration against increased protectionism.

David Wilkins says it's vital the North American Free Trade Agreement stay intact when Barack Obama takes office next year.

Wilkins told a Calgary business audience that "in our troubled world, it's a good thing to have our closest friend and ally" be the biggest exporter of oil and gas to the United States.

Obama had mused about reopening NAFTA during the presidential primaries. Wilkins noted Wednesday, however, that it was likely just "campaign rhetoric."

Once the new administration looks at all the facts and figures "it will understand that NAFTA is simply too beneficial" to do away with, he said.

Wilkins was appointed ambassador to Canada by President George W. Bush in 2005.