During his 22-year tenure as prime minister, Dr Mahathir Mohamad was swathed in allegations that ranged from abuse of power to colossal corruption.

And since he has trained his guns on the current administration, the supporters of Prime Minister Najib Abdul Razak are rummaging through Mahathir's closet for his skeletons.

One of those skeletons is national car maker Proton, the ailing brainchild of Mahathir which began operations in 1983.

A letter published on MyKMU.net has now questioned the profit accumulated by a relative of Mahathir with regard to Proton.

The writer noted how Mahathir gave the impression that Najib's stepson Riza Aziz acquired funds from 1MDB.

Riza landed in the spotlight after it was revealed he purchased a New York penthouse for RM110 million and for producing the Hollywood movie 'Wolf of Wall Street'.

The MyKMU letter stated that reports showed Proton made sales amounting to RM200 billion since the first batch of models were rolled out.

"Does Tun (refers to Mahathir's honorific title) have an interest in this? Tun is so defensive of Proton that he is willing to topple the prime minister for it.

"Hence, many are asking if Tun has a personal interest in Proton?"

The letter also said a Perkasa vice-president had sent text messages yesterdays arguing that Proton helped Malay vendors in the automotive industry.

While the writer did not deny this, he however questioned who amongst these Malay vendors reaped huge profits.

The writer then named a firm, which he claimed was the sole provider of 'rust-proofing' for all Proton vehicles.

Asking Mahathir to disclose who owned the firm's parent company, the writer alleged that it belonged to the former premier's relative (anak saudara).

"How many billions did this firm make from Proton? Is this why Tun is protecting Proton? Is this the money Tun is trying to protect?

"This letter does not intend to ruin Tun's image or bumiputera business. It is just that Tun has gone overboard in his efforts to topple the prime minister by concocting stories about 1MDB.

"If Tun is willing to slander the stepson of the prime minister, perhaps Tun must also answer the involvement of your kin in Proton for 30 years," he added.

Malaysiakini has contacted Mahathir’s aide with regard to the article and is awaiting a response.