Dr Mahathir Mohamad today denied Prime Minister Najib Abdul Razak's claim that the former premier would have tried to oust him even if 1MDB did not become an issue.

Instead, the former premier said he had given Najib ample chances but 1MDB was the straw that broke the camel's back.

"There were loads of other things that he did wrong. I could itemise them but this (1MDB) is using billions of government money; that, I cannot accept," he told a press conference in Kuala Lumpur today.

Mahathir said he had campaigned hard for Najib in the general election, which saw the return of Kedah to BN, even though he had disagreed with the prime minister for some time.

"I was prepared to support him all the way but he seems to think that if you give people money, they will love you.

"'Cash is king', that was what he told me; if you give cash to people, you become popular but I know he was not popular," he said.

Mahathir said even though he had said Najib needed to resign if he performed worse than his predecessor in the general election - which the prime minister did - he still decided to give him a second chance.

"I felt I should give him another chance, but then 1MDB came up," he said.

He criticised 1MDB's deals, such as purchasing overpriced power plants and getting cheap land banks from the government, and described these moves as "cheating".