A NSW university student who spent four weeks in solitary confinement after being falsely accused of terror offences has described the police investigation into his case as "embarrassing and biased".

Key points: Mohamed Kamer Nizamdeen has accused anti-terrorism police of arresting him because he is Asian

Mohamed Kamer Nizamdeen has accused anti-terrorism police of arresting him because he is Asian Speaking for the first time since his release from prison last month, Mr Nizamdeen said the experience had "taken a toll" on him and his family

Speaking for the first time since his release from prison last month, Mr Nizamdeen said the experience had "taken a toll" on him and his family Police dropped the charges against the 25-year-old but refused to apologise as the investigation was "ongoing"

Mohamed Kamer Nizamdeen, 25, was arrested in August after being accused of writing in a notebook about plans to kill former prime minister Malcolm Turnbull and his then-deputy Julie Bishop.

Mr Nizamdeen spent four weeks in solitary confinement in a supermax prison after being charged with the offences.

But police last month dropped the charges because a handwriting expert could not prove the 25-year-old had actually written the plans in the notebook.

Speaking at a press conference in his hometown of Colombo, Sri Lanka, for the first time since he was arrested and later released from prison, Mr Nizamdeen condemned the Australian Federal Police (AFP) for its handling of the investigation.

"The method in which the AFP conducted themselves was completely immature, unprofessional, irresponsible, embarrassing, and biased to say the least," he said.

"I strongly believe this happened because I'm an Asian, on a student visa.

"And the AFP . . . had the wrong impression that I did not have the resources or capability of defending my innocence.

"After I was charged and incarcerated, my only consolation was having faith in the Australian judicial system, which is completely independent to the Australian Federal Police."

The matter also involved the NSW Joint Counter Terrorism Team (JCTT).

Mr Nizamdeen worked in UNSW's IT department. ( Facebook: UNSW )

Police had alleged Mr Nizamdeen possessed a blueprint to target several "symbolic" Sydney locations, after officers from the JCTT arrested him at Kensington, in Sydney's south-east in August.

Mr Nizamdeen said he continually told investigators that the handwriting in the notebook was not his.

Detectives said blueprints for the attacks were found in a notebook in a desk that Mr Nizamdeen used at his workplace at the University of NSW.

"Following eight hours of questioning, detectives thought it was fit to charge me under Australian's draconian laws," he said.

"This was after I denied several times that the handwriting was mine.

"What was even more hideous was what followed afterwards.

"Nowhere in the world would you have the media circus which followed my wrongful arrest and the press conference held by [the police]."

Mr Nizamdeen's arrest received widespread media coverage including a front page on The Daily Telegraph with the headline "posterboy for terrorism".

The piece included a photo of the student wearing a Middle Eastern-style keffiyeh and dark sunglasses.

Investigation has 'taken a toll'

The sole piece of evidence against Mr Nizamdeen — the notebook — was handed to police by a colleague.

"It was discovered in an office space where I hadn't worked for over a month," he said.

Mr Nizamdeen was completing a PhD and working as a business analyst at the UNSW IT department.

He said his detainment had taken a toll on his family. He was unable to speak to them for a month after his arrest.

"It took six days for my lawyers to contact me," he said.

"I had no contact with the outside world for six days, which is a violation of basic human and fundamental rights.

"This whole saga has clearly ruined my future and I've returned to Sri Lanka to continue my life."

Police investigation 'ongoing'

Police refused to apologise to Mr Nizamdeen after dropping the charge.

They said the investigation was ongoing.

NSW Police counter-terrorism Assistant Commissioner Michael Willing at last-month's press conference. ( ABC News: Avani Dias )

Speaking at a press conference last month to reveal they had dropped the charges, the AFP and counter-terrorism officers said the "very nature" of terrorism threats meant they had to "act first".

"We can never be complacent because the terrorist threat in Australia and NSW is very, very real," NSW Police counter-terrorism Assistant Commissioner Michael Willing said at the time.

Police said the investigation had shifted to focus "on the possibility that the content of the notebook had been created by other people".

Asked last month whether the investigation had ruined the young man's life, Mr Willing replied: "I think those that are involved in the production and manufacture of these documents are the ones that have had an impact on Mr Nizamdeen."

Mr Nizamdeen's uncle Faiszer Musthapha is the Sri Lankan Sports and Local Government Minister.

Last month he told the ABC he believed his nephew was innocent.

Mr Nizamdeen's previous bail hearing heard other material belonging to the student such as his computer, mobile phone and other documents did not show any extremist ideology.

Mr Nizamdeen could sue the police for compensation over the wrongful detainment.

"I am completely exonerated, and I hope the media and the Sri Lankan public can help me pick up the pieces of my shattered life."

The AFP referred the ABC's request for comment to its statement issued at the time of the press conference last month.

NSW Police declined to comment.