The five children of a Pentecostal couple in Norway were taken from their family because their parents spanked them, not because of their religious faith, according to a lawyer close to the case.

Ruth and Marius Bodnariu lost their children to Norway's Barnevernet or children's services last November in a case that has attracted world-wide attention. It was reported that the couple's religious faith had raised concerns at the children's school and their case was taken up by religious liberty campaigners. The case also fitted others where the children of immigrant or mixed-ethnicity families had been removed; Marius Bodnariu is from Romania.

US-based Peter Costea, president of the Alliance for Romania's Families, told the Christian Post that court documents showed that the children were removed because they told investigators their parents spanked them as a disciplinary measure, not for religious reasons. Corporal punishment of children is illegal in Norway and schools are obliged to report it.

The Christian Post cites a letter to Norway's ambassador to Romania, Tove Bruvik Westberg, in which Costea described the authorities' behaviour as "totalitarian extremism".

He wrote that Norway has violated the Bodnariu's parenting rights and added that the "punishment doesn't fit the crime."

"The Bodnariu family has been accused of spanking its children. Yet, the authorities translated this accusation into child abuse, which is farthest from the truth," Costea wrote. "Biological parents have the inherent right to reasonably discipline their children. The fact that Norway has banned corporal punishment of children does not mean that Norway is right in this matter and the rest of the world wrong."

He said the authorities had been "irrational and extreme".

Costea told the Christian Post that testimony from neighbours and the school principal about the good health and wellbeing of the children had been disregarded by the Barnevernet.

At least 10 members of the Romanian parliament travelled to Oslo last week to intercede with the Norwegian authorities.

A decision about whether to put the children up for adoption will be taken in March.

A petition in support of the family has reached more than 57,000 signatures. The Barnevernet, which has refused to comment on the case citing privacy issues, has been the target of intense criticism not just from Romania but from many other countries for its policies.