KUALA LUMPUR (Reuters) - A Malaysian state’s royal council on Thursday urged authorities to investigate former Prime Minister Mahathir Mohamad for sedition over his alleged insult to those who trace descent from the southeast Asian region’s ancient Bugis seafaring community.

FILE PHOTO: Former Malaysian prime minister Mahathir Mohamad speaks during an interview with Reuters in Putrajaya, Malaysia, March 30, 2017. REUTERS/Lai Seng Sin/File Photo

Over the past few weeks, Mahathir, 93, has been sharply criticized for comments at an opposition rally last month where he is reported to have described Prime Minister Najib Razak as a “Bugis pirate”.

Mahathir’s remarks about his former protege came in the context of alleged mismanagement of billions of dollars by state fund 1Malaysia Development Berhad (1MDB), in which Najib has denied all wrongdoing.

“An investigation and legal action must be taken against Dr Mahathir under the Sedition Act, 1948, or any related laws,” the royal council of the western state of Selangor said in a statement issued by its secretary, Hanafisah Jais.

Mahathir’s comments at the rally were “excessive”, it added, and could spark hatred for those of Bugis ethnicity, besides which the speech “indirectly insults” the Bugis lineage of the sultanate of Selangor.

Selangor Sultan Sharafuddin Idris Shah urged all parties, particularly politicians, to avoid use of racial issues for political capital as this could disrupt harmony and unity, the statement said.

The police were not immediately available for comment.

Mahathir’s office did not immediately respond to a Reuters’ request for comment. The former prime minister last month said his criticism targeted only those of Bugis ancestry who stole the people’s money, news reports have said.

A body representing Malaysia’s Bugis community demanded that Mahathir apologize and retract his statement, state news agency Bernama said last month.

Thousands of Malaysians rallied on Oct. 14 in the finale of a two-month-long opposition roadshow aimed at convincing majority Malay Muslim voters in rural battleground areas that Malaysia has suffered from Najib’s handling of 1MDB.

Najib has so far been able to weather the scandal, consolidating power by clamping down on dissenters and curbing domestic media and activists, even as he faces a fierce challenge from Mahathir, who was prime minister for 22 years.

But Najib’s popularity took a hit from persistent bad press linked to 1MDB, especially after the U.S. Department of Justice filed civil suits to recover more than $1.7 billion alleged to have been misappropriated from the 1MDB fund.

Originally seafarers who hailed from Indonesia, the Bugis community established sultanates on the Malaysian peninsula.

Their Malaysian descendants are considered to be part of the Malay majority, that makes up more than half of Malaysia’s population of nearly 33 million.