The police are working to identify the mastermind behind the group of people arrested outside a gate of the Istana Negara yesterday claiming to be the rightful heirs to the throne.

Kuala Lumpur CID chief Datuk Ku Chin Wah said the police were also determining the motive of the group.

"Eight men, including the group's 40-year-old leader, have been remanded for a week from today. A 52-year-old woman, believed to be the wife of the leader, and her 11-year-old daughter have been remanded for two days until tomorrow," he told a news conference here today.

Ku said the eight men were being investigated under Section 121B of the Penal Code for offences against the authority of the Yang di-Pertuan Agong, and could be sentenced to life imprisonment or fined upon conviction.

The group, claiming to be members of the Kumpulan Panji Hitam from Timur Empayar Langkasuka Nusantara and attired in black, arrived at the palace gate at 4.10am in three cars and were detained by the police.

Meanwhile, the Islamic Development Department of Malaysia (Jakim) and the state Islamic affairs departments have offered their cooperation to the authorities in addressing the issue.

Jakim director-general Datuk Othman Mustapha said people who had information on the group could offer them to Jakim and the state departments.

"The group was detected earlier through the social media where it had revealed itself and shared information with the people though it all seemed to be absurd," he said in a statement.

The group's latest move of going to the palace reflected the members' increasing boldness to translate their ideology into action to state their desire, he added.

Othman said that though the group's doctrine was contrary to historical facts and deviant in terms of religion, Jakim was convinced it had loyal followers but not that many.

"As the group has sparked a security issue, the security authorities should be allowed to take the appropriate action," he said.