A sadist who enjoyed devising new methods of torture to inflict pain on his children has been locked up for nine years.

A judge told the fanatical Christian preacher that his campaign of long-term, calculated cruelty was "almost beyond belief".

The man's wife, also a Christian extremist, was jailed for six years.

Judge Christopher Prince described her as "a strong and forceful personality" who chose to do nothing to protect her two sons from their tyrannical father.

The couple were led to the cells in handcuffs at Bradford Crown Court yesterday.

Both sat impassively in the dock with their arms folded as the judge passed sentence. Neither can be named because of the need to protect the identity of their sons, aged 13 and 11.

During a ten-week trial, the jury heard harrowing evidence from the boys, who were mutilated, bound and beaten at their Bradford home.

The children, only seven and nine years old when the torture began, had safety pins fastened through their lips. Their mouths were sliced with scalpel blades, and the older boy's tongue was pressed with sharp pincers.

The man, 47, was convicted of 11 charges of cruelty and wounding. His wife, 41, was found guilty of two charges of cruelty.

The Crown said the man might have mutilated the boys as his interpretation of religious teaching. He told them God had his tongue cut off in the Bible.

Judge Prince told the man: "You are calculated, determined, persistent and cruel in the extreme."

He branded him manipulative, highly-opinionated, arrogant and sadistic. He said no form of religious belief could justify such behaviour.

"It is no more than self-delusion. You have sadistic tendencies and took pleasure in inflicting pain on your children.

"To all right-minded people, in particular parents, the idea of causing injury to children is almost beyond belief," the judge added.

He said the boys must have come home from school and lain in bed at night fearful of what torture their father would devise next.

"The hours and hours, and days and days, in between the infliction of the injuries must have been most awful torment for them."

Judge Prince told the boys' mother it was almost impossible to comprehend how maternal instinct did not spur her to action.

The boys, who were concealed in the family home during the school holidays so their injuries would not be seen, are now in care.

The 13-year-old, who was trussed up by his father and shut in a dark cupboard, was now so afraid of the dark he could not visit the bathroom at night, the court heard.

Prosecutor Caroline Wigin said the couple originally came from Nigeria. They moved to Austria and then to Bradford in 2003.

They lived in a small house and the boys attended a primary school in the city.

In February, 2005, a pupil saw bruising to the older boy's back and he told a learning mentor his father beat him five or six times a week.

His brother said his father swung a pole at him. He had classic defensive injuries to his fingers, Miss Wigin said.

After the boys were taken into foster care they revealed they were tortured with safety pins, clothes pegs and scalpel blades.

They said their father sewed up the wounds to their mouths with a home medical kit. Their mother picked a blunt needle because it would be more painful.

The younger boy said his mother would "just sit there". He told how he was tied to a chair, blindfolded and left all night with a safety pin through his mouth.

The man's barrister, Latiff Adenekan, said: "He was a caring father who was proud of his children. He wanted to see them neat and well-educated."

The man continued to maintain he was innocent of all the allegations.

Philip Martin, for the woman, said: "She has already been deprived of her children and she will now be deprived of her husband. Everything that she cherished has been destroyed."

She had been victimised in prison and "labelled as some sort of freak" because of her religious beliefs.