"Radical fanatics could convince my people to become killers ... they're already prone to violence because they grew up in racist, violent society," Koori Muslim Association director Rocky Davis said yesterday.

Already there were hardcore criminals, including Aborigines, at some maximum-security prisons who had converted to Wahabism - a fundamentalist branch of Islam practised by Osama bin Laden - by radical clerics or fellow prisoners.

Mr Davis, head of Redfern's Aboriginal Youth Centre in Sydney's inner south, said he regularly visited jails and was concerned about 40 Aboriginal prisoners he believed were Wahabi converts. His fears were also shared by the best-known Aboriginal Muslim: champion boxer Anthony Mundine.

Mr Davis, a 40-year-old former inmate also known as Shaheed Malik, said Aboriginal prison converts were highly susceptible.

"I've been to a few talks where imams have talked about jihad and violence and oppression and it's very, very simple to convince someone that's already oppressed to become an oppressor," he said.

"If you're disenfranchised and you're oppressed and you've got no economy and you've always been discriminated against, you're the most likely to become a terrorist, you're the most likely to become a fanatic - and that's the thing that I have to worry about because my people are disenfranchised, they're oppressed," he told The Australian.

Mr Davis, who is completing a degree in social welfare at Sydney's Macquarie University, said Wahabis were increasingly infiltrating the prison system to poison the minds of Muslims.

"Wahabi clerics, they're already in prison recruiting," he said. "Most of the Muslims in prison now are Wahabi ... including the Aboriginals."

The concerns raised by Mr Davis, who converted to Islam in the early 90s while serving a 14-year jail sentence for armed robberies and other offences, come as Muslim leaders urged the Howard Government to back a plan to tackle the radicalisation of converts. The Australian revealed this week that the Muslim community was worried about marginalised converts turning to extremist clerics.

The Australian Federal Police has also identified prisons as an emerging problem. While not an immediate issue, "the experiences overseas show that there is a potential that it will become a significant issue in the future", a spokeswoman said.

John Howard's Muslim Community Reference Group chairman, Ameer Ali, said prisoners were particularly vulnerable to being radicalised because often their only source of information was those who converted them.

"They are susceptible because they are only listening to one source of information," Dr Ali said. "We should be concerned about it."

But Sydney-based Muslim cleric Khalil Shami, who is authorised by NSW Corrective Services to visit prisons, said he wasn't aware of any radical clerics converting inmates.

Asked if there were any radical Islamic converts in NSW prisons, he said: "I can see that there is some people (prisoners) ... some of them have a different idea about the government set-up or something, but we are not allowed to speak to them alone (without security surveillance)."

Dr Ali said a major problem now being faced by the Muslim community was that many were generally being converted to Islam without first going "window shopping" to find about different aspects and branches of the religion.