The father of a family found by police in a secret basement below an isolated farmhouse was previously a member of a controversial religious sect, and may have tried to start a cult, Dutch media reports suggest.

Gerrit-Jan van Dorsten, 68, is a former member of the Unification movement, which was set up by Sun Mung Moon in 1954 and whose followers are sometimes known as “Moonies”. Police confirmed they were investigating whether religious faith was involved in the family's alleged incarceration.

Mr van Dorsten was arrested on Thursday on suspicion of “depriving people of their liberty, harming the health of others and money laundering”, Dutch police said in a statement.

“We have reason to believe that the six people involved did not stay at the premises out of free will. We are investigating whether following a certain belief in life or faith has led to the living situation in which the people were found,” the police statement said, according to the Agence France-Presse news agency.

Mr van Dorsten’s six children were found by police after the eldest, a 25-year-old man, turned up at a local bar, drank five beers and told staff he needed help.

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When officers searched the farmhouse in Ruinerwold, Drenthe, they eventually found a door hidden behind a cupboard which led to a secret basement where they found Mr van Dorsten and the five remaining children who had apparently been held there for almost a decade.

The 58-year-old Austrian tenant at the farmhouse, named as Josef Brunner, has also been arrested on similar charges to Mr van Dorsten. He was reportedly also a former member of the Unification church, though the organisation has not confirmed this.

Dutch police continue their investigation at the farm on the Buitenhuizerweg in Ruinerwold, Drenthe (EPA)

The Unification church said in a statement it was “deeply alarmed to hear of the family being held in inhumane conditions on a farmhouse in the Netherlands.” Mr van Dorsten "was briefly a member of our movement in the mid-1980s", it said, but he left in 1987.

The church's statement also revealed that Mr van Dorsten’s brother, Derek van Dorsten, remained “a long-time member” of the movement, and is quoted as saying “I have not heard from my brother since 1984”.

It added: “In addition, we are unable to confirm any records of Mr Josef Brunner, the alleged captor, having ever been associated in any way with the Unification church. We are grateful that the six victims in this tragedy are now under the care of the local authorities and pray they will be able to heal from their ordeal with time and professional help.”

Dutch newspaper Algemeen Dagblad reported that Mr Brunner had met Mr van Dorsten through the church, but that he had left Austria for the Netherlands in 2010, settled in Ruinerwold, and that neighbours believed he lived there alone. The 58-year-old is described as a furniture worker who also worked on yachts. He was regarded as “an absolute professional”, the report said.

Willem Koetsier, a Unification Church member in Amsterdam, also told the paper that after Mr van Dorsten had left the group, he travelled to Germany where it lost track of him. Mr Koetsier said he thought the man “together with someone else” had since started their own cult.

When police found Mr van Dorsten in the secret basement, he was apparently ill and in bed, having suffered a suspected stroke two years ago.

According to Algemeen Dagblad, at the time Mr van Dorsten joined the Unification movement with his brother in the 1980s, he ascribed “supernatural powers” to himself.

His wife and the mother of nine known children died in 2004. Three of Mr van-Dorsten’s children have come forward and said they left the family eight years ago. It is possible he has even more children, the newspaper reports.

Before the family moved to the farm in Ruinerwold, they had reportedly stayed at a caravan park where the children were filmed performing cult rituals including walking in circles. This apparently attracted unwanted attention, leading them to move to the secluded farm.