Editor's Note: The article has been updated with Vigneswaran's elaboration about his speech to the Dewan Negara.

Outgoing Dewan Negara president S Vigneswaran has called for the 1993 constitutional amendments relating to the monarchy to be reversed.

The MIC president, in his farewell speech, said the amendments were unconstitutional.

"It is my wish, as the retiring Dewan Negara president, to call on the government to reverse the controversial 1993 amendments which are still hotly debated.

"It is my opinion, it was unconstitutional as the amendments were made without the consent of the conference of rulers and reduced the powers of the Malay rulers.

"The sovereignty of the royal institution should be restored. I stand corrected. We should restore the powers of the Malay rulers to the time of independence," he added.

Elaborating on his speech later, Vigneswaran said he was not disputing the contents of the amendments but the procedure of how it was done.

"We are only saying the bill should have gone to the conference of rulers," he added.

Vigneswaran explained he had produced 72 pages of research on the matter and would release them to the public in the future.

"While I was the Dewan Negara president, I had conducted a research about the Malay rulers' powers and the constitutional amendments because when I became the Dewan Negara president, there was a Speakers' conference in Johor.

"Tuanku Johor decreed about the conflict (with the Federal Constitution) when the constitution was amended so when I returned, I instructed for a research to be conducted and later I was of the opinion that the amendments that reduced the Malay rulers' powers did not comply with the constitution as (the amendments) were not agreed to by the conference of rulers," he said.

According to the Federal Constitution, changes to matters relating to state boundaries, religion and royal privileges must obtain the consent of the conference of rulers.

The 1993 amendments, spearheaded by then prime minister Dr Mahathir Mohamad, saw the royalty's immunity removed with the implementation a system where rulers could face criminal prosecution in a special court.

'Rulers' powers needed to ensure stability'

In his farewell speech, Vigneswaran said the rulers' powers are needed to ensure political stability and the future of a diverse society.

He highlighted the Yang Di-Pertuan Agong's role in resolving the political crisis in February following the collapse of the Pakatan Harapan government.

"When the political crisis erupted in late February, we witnessed the important role played by the Yang Di-Pertuan Agong.

"It shows the Yang Di-Pertuan Agong and conference of rulers are important pillars of the nation. They are our hope and symbol of unity as they are not politically elected and therefore free of political elements.

"These are among the reasons why the royal institution has the potential to play a role that is not bound by the rules affecting political parties where every decision is bound by sentiment and party partisanship,” he added.

Vigneswaran also thanked Prime Minister Muhyiddin Yassin and former prime ministers Najib Abdul Razak and Mahathir for giving him the opportunity to serve as the Dewan Negara president.