Former ASIO agent says Australians 'deserve to know' what led to Bondi attack

A former ASIO agent who claims to have warned security agencies about the Bondi gunmen years before last December's terror attack says Australians "deserve to know" what led to the shooting.

The former agent, known as Marcus, is seeking to return to Australia to give evidence to the Bondi royal commission in person.

His first application for a visa was rejected, however a new application was recently lodged.

In a statement provided to the ABC, Marcus said he wants to provide whatever insights he can to understand how the shooting came to take place.

"The victims of the Bondi terror attack and their families, and all Australians, deserve to know what led to those tragic events. I want to help," he said.

The former agent spent years infiltrating Islamic extremist groups in western Sydney, working as a paid source for domestic spy agency ASIO.

His cover was eventually blown, and he fell out with ASIO, who have since described him as a "disgruntled and unreliable source" — characterisations that Marcus rejects.

Marcus has previously told the ABC's Four Corners about his interactions with the Bondi gunmen, Sajid and Naveed Akram.

He claims he warned ASIO about the Akrams years prior to the attack.

"When information about the perpetrators was first released, I felt sick — because I knew Sajid and Naveed Akram personally," he said in the statement.

"Through my prior work, I had become close to Naveed and grown concerned about the apparent radicalisation of both Sajid and Naveed.

"I had raised concerns about their radicalisation."

Marcus is currently living in an undisclosed location abroad, and has said he fears for his safety.

'Security concerns' behind desire to return

Marcus has argued he needs to return to Australia to give evidence to the royal commission and police in person. 

The royal commission and New South Wales police have both expressed an interest in speaking with Marcus, and a letter from the royal commission was provided with his first visa application.

In the statement provided to the ABC, Marcus said he needs to give that evidence onshore.

"Due to the sensitivity of the information I hold, security concerns, the need for legal protections and other factors, I have come to the view — informed by expert legal advice — that I need to come to Australia to engage with the royal commission in person," he said.

His first visa application was denied on the grounds that immigration authorities were not satisfied he genuinely intended to leave Australia.

Marcus has previously sought assistance from Australia for protection and resettlement.

Government sources have also pointed to the royal commission not formally calling Marcus as a witness, however the ABC has seen correspondence from the royal commission expressing its interest in hearing from him.

A number of whistleblower advocacy groups have aired their support for Marcus's bid to return to Australia, including the Information Rights Project, the Free Speech Union and PEN International.

The Australia Palestine Advocacy Network has also supported his bid to return.

Gabriel Shipton from the Information Rights Project says for Marcus, travelling to Australia is the safest option.

"He's in hiding in a foreign country because of the work that he did for the Australian government, because of the undercover work that he did," he said.

"There are a lot of risks around him travelling to a place where he might give video evidence, risks to his life."