The Texas Supreme Court ruled Thursday that 468 children seized from a polygamist sect must be returned to their parents, saying state child welfare officials had overstepped their authority.

The ruling upheld a lower court's finding last week that Texas child welfare officials failed to prove the children were in immediate danger when they were taken from the Fundamentalist Church of Jesus Christ of Latter Day Saints (FLDS).

Texas police and welfare officials raided the reclusive sect's sprawling compound near the small town of Eldorado on April 3 and took the girls and boys into state custody amid allegations of systemic sexual and physical abuse.

Officials said girls were being 'groomed' to accept sex with their middle-aged 'spiritual husbands' as soon as they hit puberty and boys were being indoctrinated to perpetuate the cycle of abuse.

Sect members believe that plural marriage is a way to get to heaven.

But despite the shocking allegations there have yet to be charges or arrests in the case. Police say the investigation is ongoing.

The Texas Department of Family Protective Services, which oversees the office of Child Protection Services (CPS), issued a statement promising to 'take immediate steps to comply' with the ruling.

CPS 'has one purpose in this case -- to protect the children,' the statement said.

'Our goal is to reunite families whenever we can do so and make sure the children will be safe. We will continue to prepare for the prompt and orderly reunification of these children with their families.'

A lawyer for Texas Rio Grande Legal Aid, the group challenging the state's actions, said the children must be released quickly.

'CPS should be ready now to send these kids back to their mothers,' David Hall, who heads the group, told reporters in the state capital Austin.

One of the sect mothers, Martha Emack, choked back tears as she spoke briefly to reporters.

'I'm happy as soon as all the children are back to their mothers and we're home,' said Emack, mother of a year-old infant and a two year-old toddler.

'On the record before us, removal of the children was not warranted,' the Texas justices wrote in their ruling.

It said Texas child protection authorities took possession of 'all 468 children at the Ranch without a court order.'

'The Family Code gives the district court broad authority to protect children short of separating them from their parents and placing them in foster care,' the high court said.

It suggested Texas authorities had at their disposal other methods to ensure the safety of the children, including 'restraining a party' from taking a child outside a certain area, and 'the removal of an alleged perpetrator from the child's home.'

The Texas Court of Appeals ruled on May 22 that the Texas Department of Protective Services overstepped its authority by removing children who were not in 'immediate' danger of harm.

The sect's YFZ (Yearning For Zion) ranch was purchased in 2003 and built by Warren Jeffs, the group leader, who was convicted last year by a Utah court on two counts of being an accomplice to rape relating to the forced marriage of a schoolgirl to a cousin.