Mahathir, 92, whose four-party coalition won a shock victory over former leader Najib Razak on May 9, also said reformist politician and coalition partner Anwar Ibrahim would be released from jail on Wednesday.

"(In) an initial stage, maybe lasting one or two years, I will be the prime minister," Mahathir told a Wall Street Journal conference in Tokyo via a video link from Malaysia.

"I will play a role in the background even when I step down."

Mahathir added that Anwar, after his release, would need to seek a seat in parliament and then might be given a cabinet post, but would play the same role in the coalition as leaders of the other three parties in the alliance.

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"I expect him to play the same role as the leaders of the other three parties. There will be no special powers given except as are given to ministers or deputy ministers or deputy prime ministers," he said. He added that he would make the final decision about cabinet posts.

Mahathir sacked Anwar as his deputy prime minister in 1998. Anwar then started a movement known as 'Reformasi’ - reform - to end the then ruling party's race-and patronage-based governance. However, he was stopped in his tracks by charges of sodomy and graft, which he denied, but for which he was jailed.

Anwar was imprisoned again in 2015, when Najib was prime minister, after another sodomy charge, which he described as a politically motivated attempt to end his career.

Mahathir, asked about the possible prosecution of his predecessor, Najib, said he thought that "in a short while" the government could have a case against him.

Najib's popularity dropped sharply over the past three years, partly due to a scandal over 1Malaysia Development Berhad (1MDB), a state fund from which billions of dollars were allegedly siphoned off.

Mahathir was once Najib's mentor but he the former ruling party over the 1MDB affair and joined the opposition.

Najib, who was chairman of 1MDB's advisory board, denied any wrongdoing and he has been cleared of any offense by Malaysia's attorney general.

Mahathir said that whether Najib would serve time in prison would depend on the results of an investigation.

"If there is no case, we don't go for detention without trial," he said.

Mahathir also said he welcomed foreign direct investment in Malaysia by China and other countries, but such investment must bring in capital and technology and provide jobs for Malaysians.

He also suggested that it would be necessary to limit immigration.

"Any country would like to restrain immigration from coming in large numbers," he said.

"We have the same problem. We need to restrict immigration and accept a certain number that we can deal with."

REUTERS