Umno leaders have slammed Dr Mahathir Mohamad for turning on the party, but Foreign Minister Anifah Aman said world leaders too were saddened by the former prime minister's actions.

"What they emphasised was their sadness over Mahathir's willingness to act in a manner that is detrimental to this country.

"If he disagrees (with the country's leadership), let Malaysians decide in the general election. That is the sadness they expressed because Mahathir is well respected," he was quoted as saying in an interview with Mingguan Malaysia.

Anifah also criticised Mahathir of undoing what he had achieved in his 22 years as prime minister simply because he wanted to oust Najib.

Mahathir has accused Najib of corruption and is on a warpath with Umno which has chosen to defend the latter. Najib has denied any wrongdoing.

In contrast, Anifah said world representatives, apart from seeking clarification, had no qualms with Malaysia under Najib.

"To date, there are some questions raised, but not to the extent of labelling Malaysia as all kinds of things.

"Not a single world leader I met expressed concern over Malaysia but only wanted clarification," he said.

"If they had lost confidence in Malaysia, it would be impossible for them to come to Malaysia.

"There are so many requests throughout the world, that Wisma Putra doesn't have enough time to fulfill all of them," he said.

Malaysia is embroiled in an international money laundering investigation over 1MDB's funds.

The US Department of Justice (DOJ) concluded that more than US$3.5 billion was stolen from 1MDB, with at least US$731 million going into the personal bank accounts of "Malaysian Official 1".