CHATHAM, Ont. -- An Ontario judge has "grave" concerns about the welfare of children in an ultra-orthodox Jewish sect, she wrote Monday even as she allowed an appeal from their parents.

The Superior Court judge ruled that 13 children who are part of a group known as Lev Tahor do not have to be sent back to Quebec, where much of the community fled late last year amid a child protection case.

Seven of the children are already in care in Ontario -- one set of parents took the rest and fled to Guatemala -- and to create further instability in their lives by sending them to foster care in Quebec would have "disastrous emotional and psychological ramifications for them," ruled Judge Lynda Templeton.

The case will now go back to provincial court to determine whether the children are in need of ongoing protection.

The allegations -- which include underage marriages, a lack of education and hygiene concerns -- have not been proven in court, Templeton stressed, but cause the court "grave concern about the health and welfare of these children and their protection," Templeton wrote.

"The circumstances in this case fundamentally beg the question whether the community to which the appellants belong is entitled to foster self-perpetuation by the suppression or limitation of critical thought in its children," Templeton wrote.

"There is also cogent and probative evidence before the court that the one or more girls younger than 16 years of age have been married in a ceremony sanctioned or performed by a person perceived to be a religious leader of the community."

Spokesmen for Lev Tahor have denied allegations of abuse and underage marriage, but acknowledge the children are given a religious education.

Lev Tahor, a community of about 200 people, left their homes in Ste-Agathe-des-Monts, Que., in the middle of the night, after a child welfare agency started a child protection case against a couple of the families

They settled in Chatham, but the families at the centre of the court case fled the country ahead of an appeal hearing. Some were stopped in Trinidad and Tobago and were sent back to Canada and a 17-year-old mother and her baby were found in Calgary, but six of the children and two parents successfully fled to Guatemala.

Fleeing one province for another to avoid child custody proceedings is to no avail, Templeton warned the parents.

"The state will continue to exert its pressure and influence over the family through its local agencies no matter where they are in order to ensure that the children in that family are not at risk," Templeton wrote.

Rehabilitation for the parents may be necessary to reunite them with their parents, and in the meantime, the children's aid society in Chatham shall continue investigating the families, she wrote in her decision.

Templeton's ruling overturns an earlier decision that Ontario should enforce a Quebec court order that the children be temporarily placed in foster care in that province. She said that the lower court judge erred on a question of law in determining the order should be enforced.