An ethnic Indian Hindu woman has urged Malaysia's highest civil court to stop her Muslim husband from converting their son to Islam against her wishes.

Subashini Rajasingam, an ethnic Indian Hindu married Saravanan Thangathoray five years ago and the couple has two sons -- Dharvin and Sharvind.

However, Subashini's husband told her last November that he had converted to Islam.

Subashini attempted to commit suicide and was hospitalised. When she returned home, she found that her husband had left with their son Dharvin, whom he claimed had also converted to Islam.

The woman turned to the court to prevent her husband from converting Sharvind and from seeking a divorce in an Islamic Shariah court instead of a civil court.

However, the court of appeals ruled in March that Subashini should argue her case in the Shariah court.

The federal court began hearing Subashini's appeal against the earlier verdict on Sunday where her lawyers stated that one parent cannot convert a child to Islam if the other parent objects.

The lawyers felt that a ruling from the Shariah court may affect Subashini's rights.

"With respect, only this honorable court can ensure that no such injustice occurs," her lawyers said in a statement.

"The Shariah courts have no jurisdiction since (Subashini) is not a person professing Islam," they said.

Until the federal court rules on the case, Saravanan cannot convert Sharvind, divorce his wife or seek custody of the kids.

Malaysia is a Muslim majority country where 60 per cent of the 27 million people are Muslims.

Indians, mostly Hindus, form 10 per cent of the population, while Chinese who are either Buddhists or Christians form 25 per cent.