Muslim groups nationwide have been told to be adequately prepared for the much-anticipated Federal Court decision on the Lina Joy case tomorrow .

Mosques, surau , and non-governmental organisations have been urged to hold special prayers so that the judgement is "in favour of Islam".

In making the call this morning, though, PAS Federal Territory Youth chief Kamaruzaman Mohamad strongly urged all parties to remain calm and warned against any attempts to provoke or raise tensions over the issue.

"The aim is not to antagonise any party or to create tensions. Any mistake committed by Muslims present (at the Federal Court tomorrow) will be used to denigrate the image of Islam and that of Muslims in Malaysia," he said in a statement.

"It is also not impossible that certain parties will seek to provoke or create tensions for that same objective."

He urged those who able to attend court to do so, as a demonstration of their concern "for the future of Islam in this country".

Joy, 43, whose Muslim name was Azlina Jailani, converted to Christianity in 1998. She successfully applied that year to change her name, but the National Registration Department refused to remove her religion, stated as Islam, until the state religious authorities agreed to this.

The decision to be delivered by the highest court is seen as determining the state of religious freedom as well as the extent of the jurisdiction of Syariah courts under Malaysia's parallel judicial system.

Meanwhile, the PAS-linked group Forkad and the Pembela coalition - both set up to counter the emerging cases of apostasy among Muslims - also issued guidelines for those attending court.

Every effort must be made for calm and civility and to co-perate with and abide by the instructions of the security and police personnel on duty, they said in a separate statement.

"Pembela advises all members of the public to distance themselves from any 'wild' or provocative acts or messages from irresponsible parties in connection to the announcement of the decision on Azlina Jailani," said chairperson Yusri Mohamad.