KUALA LUMPUR - Malaysia's PM Najib Razak on Tuesday (July 25) denounced the legacy of his predecessor Mahathir Mohamad as being rife with cronyism and corruption, reported local media.

He also urges investors not to believe the opposition alliance now led by Dr Mahathir, who was recently appointed chairman of the Pakatan Harapan (PH) alliance.

Speaking before the international business community, Mr Najib said it was necessary to appeal to investors to avoid placing faith in an ppposition bloc led by a man with a track record for "cutting corners" and rolling out policies that only benefited his close allies, reported Malay Mail.

Mr Najib, who is also the president of the ruling United Malays National Organisation ((Umno), rarely uses international business platforms to criticise his political foes, the newspaper pointed out. But he spoke out against the opposition at the Invest Malaysia 2017 event held here on Tuesday.

"This government..will always be straight with the people and we will always do the right by the people," Mr Najib said in his keynote address at the private event for investors.

"We will always put their interests first, from economic welfare to security even if it's not the most popular thing to do...this is also one of the reasons I am not very popular with that certain nonagenarian.

"Under his leadership many corners were cut, and the Malaysian people had to pay a very high price so that a few of his friends benefitted," the prime minister added.

Dr Mathathir, Malaysia's longest serving prime minister from 1981 to 2003, turns 92 this month (July).

PM Najib also slammed the latest leadership structure the opposition as "farcical" and "a return-to-work programme for old age political pensioners".

Alluding to veteran politician Lim Kit Siang of Democratic Action Party (DAP), Mr Najib said "the DAP leader of the last half century is now hiding behind the man who jailed him, trying to deceive Malays into thinking that former leader is their interim candidate for Prime Minister".

Mr Najib had previously said that Lim, 76, was Pakatan Harapan's de facto leader and that he "calls the shots" in the coalition and that Lim would become prime minister if Umno fell.

In response, Dr Mahathir said earlier this year the DAP adviser cannot become prime minister as the DAP is too small. "How can Kit Siang become prime minister? His party is small," he said in February, without elaborating on what he meant by DAP being "small".

Mr Najib's press secretary Press secretary Tengku Sariffuddin Tengku Ahmad last week said that Lim is the true leader of the alliance and that Dr Mahathir is just a puppet.

"While the list of opposition leaders announced shows a number of Malays, it hides the fact that the power and control is actually in the hands of DAP," said Tengku Sariffuddin in a statement.

Mr Najib on Tuesday (July 25) kept up the attacks on this front, stressing that DAP remains by far the most dominant party in the opposition. Dr Mahathir's Parti Pribumi Bersatu Malaysia (PPBM) party has only one seat in parliament while the Chinese-dominated party has 37 seats. Umno has 86 seats.

The opposition coalition PH now has four parties compared to three in the now-defunct Pakatan Rakyat which was formerly made up of DAP, Parti Keadilan Rakyat (PKR), and Parti Islam SeMalaysia (PAS) during the 2013 polls.

A PAS splinter party, Amanah, joined forces with PPBM and PKR to form the opposition alliance PH with DAP,