The country's economy can only recover with the removal of Prime Minister Najib Abdul Razak, his predecessor Dr Mahathir Mohamad says.

In a blog posting today, the long-serving former prime minister said this is the only way Malaysia's faltering economy and currency can be revived.

"If the currency and the economy are to recover, Najib must cease to be prime minister of Malaysia. Malaysians must demand for Najib’s removal.

"Only his ceasing to be the prime minister of Malaysia will the economy recover, the ringgit revalued up and the cost of living go down.

"Only after his removal can Malaysians stand tall again," he said.

Mahathir has been calling for Najib to step down over the 1MDB scandal, among others, and the worsening ringgit, which analysts predict will plunge even further in the next quarter.

He added that the call for Najib's removal was "nothing personal".

"It is because he has failed terribly as prime minister," said Mahathir.

'Country was doing fine until Najib helmed it'

The country was doing fine until Najib helmed it, he said, adding that under Najib the country's economic growth fell below those of the Philippines and Indonesia.

"The currency depreciated and share prices went down badly, creating problems for businesses, importers and exporters. The cost of living went up, especially after the goods and service tax (GST)," Mahathir said.

The 1MDB fiasco, the RM 2.6 billion in Najib’s private bank accounts and the murder of Altantuya Shaariibuu also blackened Malaysia's good name, he said.

"Never before has Malaysia become so disgraced by its own prime minister. Never before have Malaysians been so ashamed of their country," said Mahathir, who is Najib biggest critic.

The Proton chairperson also called upon all Malaysians to demand that Najib allows the investigation against him to be carried out by independent people not those appointed by him.

"Najib must allow due legal process to go on. If it is found that he had done illegal things, he should be made to resign,” Mahathir added.