KUALA LUMPUR (THE STAR/ASIA NEWS NETWORK, REUTERS) - Tun Dr Mahathir Mohamad's sudden backing of Datuk Seri Anwar Ibrahim "is driven by his deep concern about the Cabinet's decision to form a Royal Commission of Inquiry (RCI) on the 1980s forex losses", says Prime Minister Datuk Seri Najib Tun Razak.

"Dr Mahathir knows that the RCI findings could lead to criminal prosecution, so he cannot afford to have individuals highly relevant to the case such as Anwar, testifying against him," Datuk Seri Najib said in a press statement on Friday (July 7).

In June, the Prime Minister's office (PMO) issued a statement saying that a RCI would be convened to look into the billions of ringgit in foreign exchange losses incurred by the central bank in the 1980s and 1990s when Dr Mahathir was prime minister.

This follows the findings of a task force looking into the scandal that concluded the losses were greater than previously reported to the Cabinet and Parliament and that there was a prima facie case to be answered.

"It is ironic that Mahathir now needs Anwar, the man he sacked and jailed.

"Just as he now needs Lim Kit Siang, another man he jailed, because in reality Kit Siang controls the opposition as DAP has the vast majority of Parliamentary seats - whereas Mahathir's party has just one," he said.

Dr Mahathir is chairman of Parti Pribumi Bersatu Malaysia, which is part of the opposition coalition Pakatan Harapan.

In an interview with the Guardian in London earlier, Dr Mahathir said Anwar should be released from jail, where he is serving a five-year sentence for sodomy, and allowed to contest elections as he was a victim of a political vendetta.

Anwar is seen as the greatest threat to Mr Najib and his coalition, after leading a three-party opposition alliance to stunning electoral gains in 2013.

Anwar was once a protege of the veteran prime minister, Dr Mahathir, and the rising star of Malaysian politics, but they fell out in the late 1990s.

Soon afterwards, Anwar was jailed for the first time on charges of sodomy and graft, after being sacked as the deputy prime minister. He denied the charges, dismissing them as politically motivated.

He was convicted and jailed in 2013, when Mr Najib was prime minister, for another sodomy charge, which he and his supporters described as a politically motivated attempt to end his career.

But after their years of animosity, opposition to Mr Najib is drawing Anwar and Dr Mahathir back together.

Last year, Anwar endorsed a political compact spearheaded by Dr Mahathir to fight Mr Najib.

Mr Najib said Dr Mahathir's crusade "is motivated not by the national interest, but by selfish personal interest" in saving his family legacy and making his son, Datuk Seri Mukhriz Mahathir, the prime minister.

"He has no principles and will do anything - including allying with those he jailed, calling for foreign intervention in our sovereign democratic nation, sabotaging our economy, and making 100 U-turns if so required to manipulate people's minds - just as a means to achieve his desired ends.

"Anwar may fall for this, but I believe the nation will not. Because with only one Parliamentary seat, the chairman of Pribumi cannot decide who becomes Prime Minister. It would be grossly undemocratic.

"Mahathir demanded that Tun Abdullah Ahmad Badawi resign as Prime Minister, now demands my resignation, and will demand my successor resigns until his son becomes Prime Minister - whatever the cost to Malaysia.

"This time we will not let him succeed, because the democratic process must prevail, and the interests of the country must come before Mahathir's family.

"Nothing is more important than the needs of the people. So the government under my leadership will continue to focus unwaveringly on the economic welfare, social wellbeing and security of all Malaysians.

"Their interests must always come first, and we will deliver on our promises," Mr Najib said.

Mr Najib himself has been embroiled in a corruption scandal involving state fund 1Malaysia Development Berhad.

He has denied any wrongdoing, even as the fund became the subject of money laundering investigations in the United States and at least five other countries.