Minister of Communications and Multimedia Salleh Said Keruak has described Dr Mahathir Mohamad as desperate in relation to the legal suit filed against Prime Minister Najib Abdul Razak.

"He is clutching at straws," said the senator in a media statement.

"Mahathir tried to topple the prime minister through Umno. He failed. Mahathir tried a parliamentary vote of no confidence. He failed.

"Now Mahathir is trying to sue. His accusations are false, so he will fail yet again.

"Mahathir has run out of options. This action shows that he has no political channels left," he added.

This morning, Mahathir and two others filed a suit against Najib, accusing him of breaching fiduciary duties and malfeasance in public office.

The other plaintiffs are former Langkawi Wanita Umno member Anina Saadudin and former Batu Kawan Umno division vice-chairperson Khairuddin Abu Hassan.

Najib is named as the sole defendant in the claim.

The plaintiffs further claimed that Najib acted in bad faith to undermine, or cause to compromise various respective institutions involved in the probe of 1MDB scandals related to the remittance of RM2.6 billion and RM42 million or any other amount into the PM's personal bank accounts.

They are seeking a court order to declare Najib as having committed the tort of misfeasance in public office and breach of fiduciary duties by using his post as prime minister, chairperson of BN and Umno president to act in bad faith, to obstruct, intercede, impede and derail investigations and inquiries related to 1MDB.

Misfeasance is a term used in tort law to describe an act that is legal but performed improperly.

The plaintiffs are also seeking a similar declaration where Najib abused his positions to take action against Anina and Khairuddin.

Furthermore, they are seeking RM2.6 billion in exemplary damages and aggravated damages of RM42 million.

Najib has repeatedly denied any wrongdoing and blamed such allegations on those conspiring to topple him.