Malaysian students studying in Australia have been warned their scholarships are under threat if they attend a lecture by democracy icon Anwar Ibrahim.

The one-time deputy prime minister and perennial opponent of the Malaysian government, feted around the world for his decades-long campaign for democracy and the rule of law, will speak this weekend at Adelaide's Festival of Ideas.

For 15 years Mr Anwar has been a leading figure in the Malaysian opposition, and for 15 years he has been dragged in and out the courts on trumped-up charges of corruption, and more sensationally, sodomy.

He was beaten and gaoled until the sodomy charge was thrown out by the supreme court and he was released, only to be charged again in 2008. Again he was acquitted, but the Malaysian government wants him tried again.

Now, the government has warned Malaysian students that their scholarships are under threat if they attend Mr Anwar's lecture.

An email from the student adviser at the Malaysian consulate in Sydney has warned students to make sure their scholarship "does not go down the drain".

"Please refrain yourselves from further joining this activity. You are smarter to think and focus on what matters, rather than joining this activity that could make your hardship in maintaining good grades and earning the scholarship goes down the drain," the email said.

"I wouldn't hesitate to take stern action to those scholars who involved. You know really well what you've signed into."

The email is signed "the one who cares," student advisor Shahrezan Sheriff.

Students maintain scared silence

Many Malaysian students approached by 7.30 were too frightened of the consequences to speak publicly.

However, one student not on a scholarship spoke to 7.30 on condition of anonymity.

"Yes, I am really disappointed because I thought of asking my friends who are JPS scholars if they would like to go with me tomorrow," the student said.

"They didn't even reply."

Mr Anwar says it is not the first time the Malaysian government has tried to gag him overseas.

He says the students should not be intimidated and "if anything happens to them we will raise an uproar".

"This form of intimidation is crossing the line," he said.

'We want them to feel confident': Xenophon

Senator Nick Xenophon has been a long time supporter of Mr Anwar, and on a parliamentary visit to Malaysia earlier this year he was detained for sixteen hours at the airport before being deported.

The Malaysian government has since banned him from the country for attending an opposition rally there last year.

"The Australian Government needs to make it absolutely clear to the Malaysians that as a matter of urgency sometime on Friday that these threats are completely unacceptable," he said.

"These students have a right to attend this forum involving Malaysia's opposition leader without any fear of retribution.

"The level of paranoia amongst the Malaysia government is just extraordinary."

Sophie Black, the director of the Festival of Ideas, says she is concerned for the students.

"We want them to feel confident that they can attend the event without consequences, without those sorts of consequences especially," she said.

"I think it is absolutely vital that they can feel free to attend something like this, that they can sit in the audience of someone that they admire and listen to them speak."