The statement by the Conference of Rulers on 1MDB appears to show that the sultans are not confident with Prime Minister Najib Abdul Razak, said an analyst.

John Pang, a senior fellow at the S Rajaratnam School of International Studies in Singapore, said this is because the Malay rulers have never been so specific on a government issue.

"The statement adds to the sense that he (Najib) has lost the confidence of the Malay Rulers, along with other important sectors of society,” Pang is quoted as saying by The New York Times .

Institut Darul Ehsan (IDE) chairperson Redzuan Othman voiced similar views that the sultans' statement was unprecedented.

"This (1MDB issue) is very serious, or else the sultans would not step in.

"Usually, the sultans would only comment on issues regarding Islam or Malay interests and they would not step in on issues of governance," Redzuan ( photo ) told Malaysiakini .

The Conference of Rulers on Tuesday decreed that the investigation into 1MDB be completed as soon as possible and the wrongdoers, if any, be punished.

They said if the 1MDB issue is not dealt with intelligently, and continues to drag on, it will damage the economy and the people's welfare.

Pang said: "This (stand of the royalty) will embolden both the civil service and civil society groups that are dismayed by the scandal."

Redzuan added that the royal decree would also help to pacify the people, who he said only want to know the truth.

US financial daily The Wall Street Journal has reported that 1MDB funds had made their way into Prime Minister Najib Abdul Razak's personal bank accounts.

Najib, however, denied any wrongdoing or that he had used 1MDB funds for personal gain.