A British mother has been jailed for seven-and-a-half years for helping to snatch her children from US social workers at gunpoint.

Ruth Christine, 29, from Launceston, Cornwall, was sentenced to 90 months at the hearing in Roseburg, Oregon, after going on the run with her three daughters who had been taken into care because of fears of mistreatment.

Her American husband Brian Christine was jailed for 12 years for holding the Magnum pistol used in the raid.

The couple, who met when they studied together in the University of Kent, Canterbury, in the mid-1990s, were convicted in May of robbery, custodial interference and unauthorised use of a vehicle at Douglas County Circuit court.

The family were passing through Grants Pass, Oregon in July 2000, living on a bus, when police took six-year-old Bethany, Lydia, four, and three-year-old Miriam into protective custody.

Doctors said the girls were malnourished and had to spend several days in hospital before a judge placed them in foster care.

Following a supervised visit to the children in August 2001, Brian Christine put a gun to one welfare worker's head and demanded his daughters were returned.

The couple fled with the girls but were arrested several days later in Montana after being stopped for speeding.

Ruth Christine wept as she told the court she was sorry for the trauma suffered by the two child welfare workers in the kidnapping.

"I didn't believe that this day would come. Today, all I want is to be with my husband and children. Those are my only desires in this whole world."

Her husband told the judge he would not ask mercy from the court, only from God. The children have been adopted by their mother's parents in Cornwall.