Since launching his campaign against Prime Minister Najib Abdul Razak, former premier Dr Mahathir Mohamad has been redrawing the political battlelines, recruiting troops from both sides of the divide.

He has now launched his latest salvo using DAP organ Roketkini.

In an exclusive interview with the online publication, the former premier is asked about his role as a mentor to Najib and whether the latter is employing lessons gleaned from him.

The disappointed master, however, disagreed.

"Many learned from me, not all followed (my teachings). But this one (student) failed. This one (Najib), his intentions are different," he said.

Mahathir also lashed out at Umno and complained about the scourge of corruption plaguing the nation.

The former Umno president, who quit the party in protest against Najib, claimed that division leaders are preventing those with calibre from joining.

"When he (the division leader) dies, who replaces him? Someone dumber than him. Umno (now) has shrunk into a party led by dimwits (orang bodoh) without principles," he said.

On the issue of corruption, Mahathir claimed that government servants are learning from politicians.

"... Because they see leaders taking billions, so how can he (the government servant) just take one or two million," he said.

In the interview, Mahathir also outlined the differences between Najib and him, lamenting how the late author Barry Wain had made him a victim for the sake of sensationalism in order to boost sales in the book 'Malaysian Maverick: Mahathir Mohamad in Turbulent Times'.

"Najib has debts. I don't have debts. I did not allocate government funds for myself. When there was an allocation, it was in the hands of the civil servants. I was not involved in changing the money from here to there

"Najib is the principal in 1MDB. His signature is required for everything. He is the CEO in 1MDB despite calling himself the adviser," he said.

On another matter, Mahathir vowed to campaign in the upcoming Sungai Besar and Kuala Kangsar by-elections.

However, the 91-year-old former Kubang Pasu lawmaker clarified that he has no intention of contesting.

"I don't want to be the candidate. I am too old. Those who support the Citizens’ Declaration must back whoever is opposed to Najib," he said.

The prime minister has denied abusing public funds, blaming such allegations on Mahathir and those conspiring to topple him from power.