'I will dig until I find the source of the worms' - that's what former Prime Minister Mahathir Mohamad has vowed to do over a number of decisions which he has taken issue with the government.

In his first public comments after keeping silence for a week as he was hosting an international anti-war conference, Mahathir renewed his scathing criticism against his handpicked successor, Prime Minister Abdullah Ahmad Badawi.

He told a 500-strong crowd at a public lecture this morning in Taman Melawati, Hulu Kelang, that he was not satisfied with the response from the government after his blistering attack on Abdullah two weeks ago.

However, Mahathir apparently wants more than just an explanation from the government.

"It is not only about explaining, such as the cancellation of the half-bridge project. They must right what is wrong. If you say cannot (proceed with the bridge project), I will dispute that," said Mahathir in his usual combative tone at a press conference after his one-hour lecture.

The lecture - Diologue with TDM (Tun Dr Mahathir) - was jointly organised by former Umno politician Ibrahim Ali and online news portal Malaysia Today.

Among the audience were former deputy home minister Megat Junid Megat Ayub, former New Straits Times editor-in-chief A Kadir Jasin and top PAS leaders - Nasharuddin Mat Isa, Husam Musa, Mahfuz Omar and Salahuddin Ayub.

Mahathir singled out International Trade and Industry Minister Rafidah Aziz for criticism, who earlier this week said that she had nothing more to explain to her ex-boss about the controversy surrounding the issuance of Approved Permits (APs).

"She hasn't explained anything. She must explain why she gave APs in such big numbers (to a select group of people) [...] She must answer why are these two (individuals) still receiving APs to import cars and also selling the APs," he said.

It was revealed last year that two former top staff from Rafidah's ministry had benefited from receiving large numbers of APs.

Same tune from Proton

Mahathir also brushed off Proton's reply to some of the questions raised by him, such the 'axing' of Tengku Mahaleel Ariff as the CEO of the national car manufacturer and the selling of Italian motorcycle company MV Augusta for a song to a 2-euro company.

According to the former premier, there was nothing new in the reply made by Proton chairperson Mohamad Azlan Hashim which was reported last Saturday.

According to Mohamad Azlan, Proton decided to drop Tengku Mahaleel to "strengthen and improve" the company while MV Agusta was sold on grounds that, among other reasons, it was a motorcycle company.

In his lecture earlier, Mahathir slammed Proton for "sacking" a CEO that had kept the company profitable and argued that losses were made only after the appointment of Mohamad Azlan.

He also defended the purchase of the debt-ridden MV Agusta Motors for RM367.6 million - made during his administration - as it would have injected much-needed technology, in particular small engines, into Proton.

Mahathir contended that even reputable carmakers such as Honda, BMW and Suzuki had all began as motorcycle manufacturers.

MV Augusta was sold to investment company Gevi SpA for a token sum of one euro (RM5) late last year.

Go ahead, sack me

Mahathir also dismissed the suggestion that he was supporting the opposition with his stinging criticism of the government.

"No way. I'm not involved with the opposition. I'm on my own," he replied to a question at the press conference.

Mahathir was unperturbed by rumours that he could be sacked from Umno due to his recent antics.

"Pecat, pecat lah (Go ahead and sack me). I have been sacked before," he said.

Mahathir also brushed aside a question on whether he saw himself as the reason why the ruling Barisan Nasional coalition and the Umno supreme council hurriedly held meetings over the past two weeks.

"You people say that they are disturbed by what I say. But from what I see, everyone agrees with the prime minister," he retorted.

He was referring to the cabinet ministers and other BN leaders who have all thrown their weight behind Abdullah.

To another question, he took a jab at his former deputy, Musa Hitam, for suggesting that he was suffering from 'Post-Prime Ministerial Syndrome', or 'PMS'.

"Musa was the one that was really sick. That's why I gave him a job (as Malaysian special envoy to the United Nations).

"(But) I didn't ask for a job (after retiring). Petronas gave it to me (as advisor). But they never ask me for advice - they just give me money," said Mahathir with his usual dose of sarcasm.