North Korea has released a young mother who was expected to be sentenced to life in a prison camp, in an unusual move that offers rare hope for a potential improvement in human rights during an ongoing thaw of international diplomatic ties.

Koo Jeong-hwa was detained in early November after she crossed into China with eight other would-be defectors, including her four-year-old son, in an attempt to join her husband Taewon Lee who was already in South Korea.

In an emotional interview with The Telegraph, Mr Lee, 29, said he had “collapsed on the floor” when he first heard of their arrest. Fearing they would sent to prison camp or killed, he pleaded with the South Koreans and international community to prevent their repatriation.

“Even if they forgive my son, his background will be that his father went to South Korea, his mother was in prison camp or executed. He will have no family, maybe he will become a street child,” the devastated father said.

Despite his efforts, the Chinese returned his family and Ms Koo was held in a detention centre in the northwestern city of Hoeryeong, accused of committing treason.

Her son was initially imprisoned with her but sent to his grandmother after 20 days, suffering from frostbite on his hands and feet.