Australian senator Nick Xenophon has expressed support for the Bersih 5 rally that is to be held in Kuala Lumpur tomorrow.

"As a great friend of Malaysia, Australia must tell it, and the world, the truth.

"And the truth is the corrupt regime that rules Malaysia with an iron fist is a destabilising and destructive influence in our region.

"All Malaysians deserve a clean government, elected through clean elections," Xenophon said in a statement today.

Xenophon, a friend of jailed PKR de facto leader Anwar Ibrahim, was present during the Bersih 3 rally in 2012.

He was tear-gassed during the protest and subsequently banned from entering the country.

In this statement, Xenophon recalled his meeting with Anwar in 2012, the last time he was allowed to enter Malaysia.

"Anwar believes the scrutiny and transparency that go hand-in-hand with a robust democracy have been absent in Malaysia, and the resulting cronyism and corruption have been key factors in Malaysia's relative stagnation.

"Those concerns have been proven by Anwar's subsequent imprisonment on trumped up charges and the latest multi-billion dollar scandal involving 1MDB," Xenophon said.

He said Australia needed to show leadership in holding Prime Minister Najib Abdul Razak's government accountable.

"Anyone and everyone who cares about the future of our region, the future of our great friend Malaysia, must heed the words of Winston Churchill: 'Never give in, never give in, never, never, never'," Xenophon added.