Business student was accused of writing in a notebook plans to kill top Australian officials and ‘lone wolf’ attacks.

The lawyer of a prominent Sri Lankan student who was accused of plotting to assassinate Australian politicians said he will sue police after prosecutors dropped terrorism charges on Friday.

Mohamed Kamer Nizamdeen, 25, was arrested in August and accused of writing in a notebook plans to kill then-Prime Minister Malcolm Turnbull and then-Foreign Minister Julie Bishop.

Police also alleged the PhD student possessed plans to carry out a “lone wolf” attack on several public places, including the Sydney Opera House, and he appeared to have links to the Islamic State of Iraq and the Levant (ISIL) group.

Nizamdeen, a respected business student at the University of New South Wales, spent four weeks in jail after being charged with making documents to facilitate terrorist acts.

He was kept in solitary confinement in a maximum-security prison along with convicted murderers.

Prosecutors withdrew the charges in Sydney’s Central Local Court on Friday. He had been released on bail in September after police admitted an expert concluded it could not be proved the plot was in his handwriting.

‘Unforgivable circumstances’

Nizamdeen’s lawyer, Moustafa Keir, told reporters outside court his client would apply for legal costs and sue the police.

“What authorities have done to this young man is absolutely unforgivable,” Kheir said.

“We will be seeking justice for him in the NSW Supreme Court. It’s a terrible experience, as a young man who has done everything right in life, he has gone through supermax jail in unforgivable circumstances.”

After Nizamdeen’s arrest, family members and hundreds of supporters in Sri Lanka held protests urging a swift and fair investigation.

Nizamdeen comes from a prominent Sri Lankan family. His uncle Faiszer Musthapha, the country’s sports minister, insisted his nephew was innocent.