Malaysia's Prime Minister Najib Razak announced the dissolution of parliament yesterday, paving the way for a general election showdown with his old mentor and the country's most seasoned campaigner, Mahathir Mohamad.

Najib is under pressure to deliver an emphatic win for the Barisan Nasional (BN) coalition, as he struggles to appease Malaysians unhappy with rising costs and a multi-billion dollar scandal at a state fund he founded.

The 64-year-old leader is expected to retain power due to a rift in opposition ranks between Mahathir's bloc and the Pan-Malaysian Islamic Party.

But analysts predict a tough fight from Mahathir, who transformed Malaysia into an industrial nation from a rural backwater during his iron-fisted 22-year rule until 2003.

The opposition says the election will be unfair. Mahathir, 92, who was himself criticised for his authoritarian premiership, told a news conference Malaysia's 14th general election would be "dirty".

"Should Najib win this election through his tricks and his cheating, then we can kiss goodbye to democracy in the 15th, 16th, 17th elections," Mahathir said.

In recent days, parliament approved plans to redraw electoral boundaries and passed a contentious anti-fake news bill, changes critics say will favour Najib.

The government rejects the accusations. Polling must be held within 60 days of a dissolution.

With the common goal of taking down Najib, Mahathir has joined hands with his former deputy and jailed opposition leader, Anwar Ibrahim, ending a feud that had shaped the country's political narrative over two decades. If elected, Mahathir would become world's oldest PM.

Najib's United Malay National Organisation (UMNO) party heads the ruling coalition that has held power since Malaysia's independence in 1957.