Tens of thousands of Malaysians rallied in the capital on Saturday to support the adoption of a strict Islamic penal code, a proposal religious minorities fear could infringe their rights.

Prime Minister Najib Razak has thrown his weight behind the contentious bill, which seeks to incorporate parts of the Islamic penal code, or "hudud", into Malaysia's existing Islamic legal system.

Najib, who is currently embroiled in a corruption scandal, is hoping to burnish his Islamic credentials in order to boost his chances in national elections that must be held by August 2018.

Critics of the bill warn that it could pave the way for full implementation of hudud, which prescribes punishments such as amputations and stoning, and disrupt the fabric of Malaysia's multi-cultural and multi-religious society.

"The so-called 'empowerment' of the Shariah Court will only exacerbate the unequal treatment of Muslims and non-Muslims before the law," said Bebas, an NGO that organized a smaller counter-rally.

No official figures were available on how many people attended Saturday's peaceful support rally in Kuala Lumpur, but estimates were in the tens of thousands.

Tuan Ibrahim Tuan Man, deputy president of the hardline Islamist opposition Parti Islam-se Malaysia (PAS), one of its organizers, said 100,000 people were expected to attend.

The PAS presented the bill in parliament last year but later withdrew it in order to fine tune the legislation. It is now expected to be reintroduced in the next parliamentary session, in March.

Najib, who has resisted calls to resign over a scandal at state fund 1Malaysia Development Berhad (1MDB), where he was an adviser, backed the bill despite the anger of members of his own United Malay National Organisation (UMNO) ruling coalition.

Lawsuits filed by the U.S. Justice Department in July last year said nearly $700 million of the misappropriated funds from 1MDB flowed into the accounts of "Malaysian Official 1", who U.S. and Malaysian officials have identified as Najib.