58-year-old Curtis Cheng (L) was shot as he left work for the day. (Photo: NSW Police)

Four men have been formally charged with plotting the murder of New South Wales police accountant Curtis Cheng.

The men are accused of planning the Sydney terror attack which led to the 58-year-old’s death in October last year.

Mr Cheng was gunned down outside Parramatta Police Station by 15-year-old schoolboy Farhad Jabar on October 21.

Jabar was later fatally shot by police officers at the scene.

Addressing the media, NSW Deputy Police Commissioner Catherine Burn said all four men were facing the serious charge of conspiracy to prepare for and commit a terrorist act.

The offence carries a maximum penalty of life in prison.

“The four men we have laid charges against have had charges laid against them previously since October 2,” Ms Burn said.

“An 18 year-old from Guildford will be charged with directing the terrorist organisation.”

Police will also allege that another 20-year-old helped Jabar’s sister travel to Syria, the day before Mr Cheng’s murder.

All four men will be charged with membership of a terrorist organisation.

They will appear before court on Thursday.

– TiVi Tuan-san