AN Australian woman caught sneaking her Mexican boyfriend illegally across the US-Canadian border has avoided a jail sentence.

Sarah Louise Branch, 37, from Sydney, was sentenced in the US District Court in the northeast state of Maine on Wednesday to a time-served sentence of 70 days.

US immigration authorities are expected to transport her immediately to the Canadian border where she will be released.

She entered a guilty plea to a charge of encouraging and inducing the entry of an illegal alien into the US.

Prosecutors told the court Branch and Benigno Godinez-Cortez, 46, hatched a plan in July for him to sneak across the border into the US.

Branch has been held in US custody since her July arrest and the court was told she was a model prisoner.