Former prime minister Dr Mahathir Mohamad today reiterated that he would not rejoin Umno even if his successor Najib Abdul Razak steps down.

In a video that he uploaded to social media, he explained that this was because he rejected Umno, which he claimed had become a “rotten” party that was focused on obtaining "dedak" (bribes).

Mahathir, who is also Pakatan Harapan chairperson, was asked if he would return to Umno, a party which he had once helmed for two decades, if Najib was no longer prime minister.

"Initially, I tried to oust Najib, not Umno. But I found out that Umno was badly rotten, as they only prioritise their self-interest and their money instead of fighting for religion, race, and the people.

"Umno is no longer the same party as it was before, as it has been moulded by Najib and it has a different purpose from the Umno that was originally established.

"That's why I am not going to return to Umno, the party which is rotten and prioritises its struggle for dedak instead of religion, race, and country," he said.

Mahathir, who left Umno for the third time in February 2016 and formed Bersatu together with former deputy prime minister Muhyiddin Yassin.

Despite his criticism of Najib, many believe that Mahathir might once again return to Umno if the opposition manages to unseat Najib in the next general election.

However, Harapan leaders have expressed their trust in Mahathir, with PKR secretary-general Saifuddin Nasution Ismail telling Malaysiakini last week that Mahathir had long “crossed the red line” when it comes to Umno.