An American sex offender was temporarily released from custody and ordered to live at his family's home in Canada on Friday, after an immigration official said the man posed little threat to society.

"I'm satisfied that as a danger, you're at the low end," said Ken Thomson, the immigration review board member who gave the ruling in Niagara Falls, Ontario.

Malcolm Watson pleaded guilty in a suburban Buffalo, New York, court on Monday to misdemeanor child endangerment and sex abuse charges involving a 15-year-old student at Buffalo Seminary, a private girls' school where he chaired the English Department.

In exchange for the plea, Watson, a U.S. citizen who lives in St. Catharines, Ontario, with his Canadian wife and three children, was placed on three years' probation to be served in Canada, and told to return to the United States only to see his probation officer.

He was detained Thursday by Canadian border guards as authorities moved to bar him from the country.

His arrest came amid furious opposition to his sentence, with Canadian officials warning against allowing the country to become a "dumping ground" for U.S. sex offenders. The federal government wants Watson kicked out of the country.

Prime Minister Stephen Harper said Friday that his government would do everything it could under the law to have Watson removed.

"The government's view is we will use every legal means to not have this individual free in Canada, which we don't think is appropriate," Harper said. "He is, however, unfortunately, a Canadian resident and Canada's laws in this regard are too loose."

The 35-year-old teacher looked relaxed and smiled from time to time, sitting next to his wife, during the proceedings in the Canadian border city of Niagara Falls.

The immigration official imposed a C$5,000 performance bond, which must be paid if Watson violates the conditions of his release.

He was also ordered to report for an admissibility hearing, expected in the next several weeks, where it will be decided if he will be ordered removed to the United States.

Already making regular visits to his probation officer in Buffalo, Watson was ordered to cross over only at the Peace Bridge and report to an immigration officer each time.

Among those criticizing the sentence was Ontario Premier Dalton McGuinty, who said he did not want his province to become "some kind of dumping ground for convicted offenders (from) south of the border."