"We will be appealing to the Federal Court," saidKindergarten teacher M Indira Gandhi'slawyer, M Kulasegaran.
On December 30 last year a Court of Appeal panel decided that the issue whether a person was a Muslim or not was only to be decided by the Shariah Court.
"It is purely a matter of religion," the judges had said.
The children had been converted to Islam by Indira's ex-husband Muhammad Riduan Abdullah, formerly known as K Patmanathan.
More From This Section
On April 2009, Riduan had taken away Prasana Diksa, then 11 months old, and converted the child and two siblings - Tevi Darsiny, then 12, and Karan Dinish, then 11 - to Islam.
The two older children remained with their mother.
Later Riduan obtained a Shariah Court order that awarded him custody of the children.
In a custody battle that ensued, the Ipoh High Court granted Indira full custody of all three children and on March 11, 2010, Riduan was ordered to return Prasana to Indira.
Malaysia is a Muslim majority country with ethnic Indians, mostly Hindus, forming eight percent of the 28 million population.