Four men charged with planning the murder of Curtis Cheng may have come together on the day of the police accountant’s murder, police say.

The men – aged 18, 20, 22 and 23 – have been charged on Wednesday with conspiring an act in preparation of a terrorist attack, almost seven months since Mr Cheng was shot dead by 15-year-old Farhad Jabar in Parramatta.

Deputy Commissioner Catherine Burn said she couldn’t say for certain others wouldn’t be charged but labelled the men “principals” in the killing.

• More charges in Curtis Cheng murder

Police will allege the men worked in concert with Mr Jabar, who was shot dead by police following the attack, to commit the “heinous” crime, she said.

“We have come across information that suggests to us that they did come together at least the day of and perhaps even the day before,” she said.

The 18-year-old man is accused of supplying the gun that was used in the murder and has been charged with directing the activities of a criminal group.

The 20-year-old organised the travel of Jabar’s sister to Syria on the day before the attack, Ms Burn said.

All the men have already been charged with other offences since Mr Cheng’s death, including knowingly making funds available to a terrorist organisation and aiding the commission of a terrorist act.

They are expected to appear in Goulburn Local Court via video link on Thursday.

“It is important that the community is assured that as of today there is no new specific threat,” Ms Burn said.

“However, we will continue to investigate any threats that we come across.”

-AAP