KUALA LUMPUR - Former Malaysian leader Mahathir Mohamad said on Sunday that he will not work with the opposition, despite his recent attacks against Prime Minister Najib Razak.

"No, I'm not working with anyone to bring down Najib, certainly not the opposition.

"The problem is within Umno itself," the former premier told reporters at the Putra World Trade Centre on the sidelines of an anti-war forum he was attending.

Tun Dr Mahathir, however, said that Najib should understand the sentiments of the people and it was best for him to resign as Prime Minister.

"One has to remember the results of the 13th general election. Najib's performance was worse than Pak Lah's (Abdullah Badawi).

He added that Mr Najib was not receiving support, despite the number of people who have pledged their support.

"Believe me, he is not getting the support that he needs," he said.

On Saturday, Democratic Action Party (DAP) adviser Lim Kit Siang had said that he was ready to put aside past problems and work with Dr Mahathir if that is what it takes to save the country.

"For this formidable task, we must be prepared to put our differences in the past to one side and concentrate all our energies on one common agenda, to save Malaysia from all centrifugal forces to tear the country asunder.

"On this agenda, I am prepared even to work with Tun Mahathir to 'Save Malaysia'," Mr Lim had said in a transcript of a speech to Malaysian students in Egypt published on his blog.

Mr Lim was referring to the "Save Malaysia" coalition, which he had first spoken about last month.

Meanwhile, Tan Sri Muhyiddin Yassin, who spoke at the Sunday forum which was attended by Dr Mahathir and his wife Tun Dr Siti Hasmah Mohd Ali, praised Dr Mahathir for never shying away from the truth.

"Telling the truth and standing up has been your trademark since you were a young doctor and an ordinary Umno member...Let me assure you, sir that you are not alone," said Mr Muhyiddin during his keynote speech.

He added that Dr Mahathir had always stood up for what he believed in and saluted the former prime minister for having the guts to stand up to world superpowers in making a stand against war.

Although Mr Muhyiddin's comments at the forum stirred speculation that it was a nod to Dr Mahathir's recent calls for Mr Najib to answer his critics over the debt-laden state fund 1MDB and other controversial issues, Dr Mahathir quickly brushed off the suggestion.

He told reporters after the event, Mr Muhyuddin was merely referring to Dr Mahathir's role in speaking up against war crimes.

"It's about this war, I'm talking about the war, and I think he's supporting me for the war," Dr Mahathir stressed to reporters, according to Malay Mail Online.