Leaders from across Malaysia's political spectrum said on Sunday (March 27) they plan to present a petition to the country's Islamic royalty seeking the removal of scandal-plagued Prime Minister Najib Razak over a corruption crisis, AFP said.

The highly unusual grouping of heavyweights from the ruling party, the opposition and civil society groups was formed in early March, when it issued a call to "save" Malaysia from disaster by removing Najib.

A succession of speakers pressed that demand during a rally attended by several hundred supporters on Sunday, accusing Najib of using his office to thwart scrutiny of the graft allegations and avoid justice.

"(Najib's) leadership undermines the very existence of our institutions," said former prime minister Mahathir Mohamad, around whom the movement has coalesced.

"We want the rule of law and the actions of Najib has destroyed it. He no longer deserves to be the prime minister," he said at the gathering near the capital.

The 90-year-old Dr Mahathir, who dominated Malaysia as premier for 22 years before retiring in 2003, has for months spearheaded calls for Najib's removal.

Najib, 62, is under pressure over allegations that billions of dollars were stolen from a state firm he founded, and over his own acceptance of a mysterious US$681 million (S$935 million) payment from overseas.

He denies accusations that the huge payment was siphoned off from the now-struggling state firm, 1Malaysia Development Berhad (1MDB), saying he is the victim of a political conspiracy.

But Najib has fuelled anger and suspicion by curbing investigations, purging critics from the government and cracking down on media reporting on the subject.

The outrage has been strong enough to unite formerly bitter political foes such as Dr Mahathir and leaders of opposition parties in the push to remove Najib.

There is as yet no indication that the movement will succeed.

(With inputs from AFP)