A German court has jailed a couple for repeatedly sexually abusing their young son and selling him to paedophiles online for more than two years.

In a case that shocked the country and raised serious questions about child protection services in Germany, the regional court in Freiburg sentenced the boy's mother to 12-and-a-half years in prison.

Her husband, the boy's stepfather whom he called "papa", received a 12-year sentence followed by preventive detention.

The stepfather had a previous conviction for child abuse, raising questions why he was allowed to live in a home with a child present.

The court found that the unemployed couple had sexually assaulted the boy, now ten, and sold him on the so-called darknet between May 2015 and August 2017.

They were convicted of rape, aggravated sexual assault of children, forced prostitution and distribution of child abuse images, judge Stefan Buergelin said as he read out the verdict.

The couple was also ordered to pay a total of €42,500 in damages to the boy and another victim, a girl.

Their sentences fell short of what prosecutors had demanded - 14 years and six months for the woman and 13 years and six months for the man.

Yesterday, the same court sentenced a Spanish paedophile to ten years in prison for repeatedly sexually abusing the young boy after paying the parents.

The 33-year-old was also ordered to pay €18,000 to the young victim.

The case came to light following an anonymous tip-off last September, and led to the arrest of eight people who have been charged with belonging to an online paedophile ring.

The stepfather admitted on the witness stand to the assaults on the boy.

He also made serious accusations against the child's 48-year-old mother, who confessed to the crimes but remained largely silent about any possible motive during the trial.

In his verdict, Judge Buergelin said the mother went along with the abuse at first so she would not lose her husband as a partner and later "for financial motives".

They charged several thousand euro for each instance of abuse, filmed the acts and posted them on the darknet.

The boy is in foster care. His lawyer told reporters today that he was doing well "under the circumstances".