Malaysian Prime Minister Najib Razak called his former mentor Mahathir Mohamad a 'traitor,' even as the slugfest between the two senior leaders hit a new low.

Najib, speaking at a Malay community event, said the former prime minister was a traitor who was cooperating with the "enemies" of the Malays.

Embattled Najib, who is trying to shake off numerous financial scandals, said Mahathir betrayed the Malays by joining ranks with the opposition.

Najib did not personally take out his worst detractor's name in the speech, but the comments topped off an ongoing slanging match between the two that started when Mahathir publicly raised the demand for Najib's resignation.

Najib sought to direct the Malay anger against Mahathir, saying the former prime minister's move weakened the ruling United Malay National Organisation (Umno), which ensured the community's prosperity and political fortunes.

"We shouldn't be sitting together and conspiring with those who want to betray UMNO. If he was once a leader he should know to defend the present leadership," Najib said, according to TODAY.

Mahathir, who has fallen out with both of his chosen successors in the prime minister's seat -- Abbdullah Bawadi and Najib Razak -- turned against the current prime minister when allegations of corruption against Najib surfaced.

In the latest salvo fired by Mahathir, the former PM asked followers to sign up a controversial Citizen's Declaration seeking Najib's resignation.

Mahathir says Najib abused his power and tried to scupper an investigation into the corruption at 1 Malaysia Development Berhard. The political patriarch stepped up his calls for Najib's resignation after it emerged that the prime minister had received hundreds of millions of dollars into his personal accounts.

The funding scandal escalated, with almost half a dozen countries opening investigations into financial irregularities at various levels, but Najib stuck to his stance that he was innocent.

The fight between Najib and Mahathir came to a head when Najib orchestrated the ruling Umno establishment's support to oust Mahathir's son Mukhriz from the position of the chief minister in Kedah province.

Mahathir quit the ruling party saying it had become 'Najib's party' and quit his government-linked positions, leading to a long trail of attacks and counter attacks.

Further dwindling Najib's standing, the latest revelations in the Panama papers showed that his family had used the services of Panamanian law firm Mossack Fonseca in hiding wealth.