A man who allegedly planned a terrorist act by attempting to smuggle a bomb hidden in a meat grinder onto an international flight in his brother's luggage, volunteered to do it himself after the plan was aborted, a Sydney Court has heard.

Key points: The Crown alleges the plot was abandoned because the bag with the meat grinder was too heavy

The Crown alleges the plot was abandoned because the bag with the meat grinder was too heavy It also alleges the pair planned a poison gas attack after the bomb plot was abandoned

It also alleges the pair planned a poison gas attack after the bomb plot was abandoned The men have pleaded not guilty to conspiring to plan a terrorist act

Khaled Khayat and his brother Mahmoud Khayat are on trial at the Parramatta Supreme Court for conspiring to prepare or plan a terrorist act.

Both men have pleaded not guilty.

Crown prosecutor Lincoln Crowley, QC, told the jury the men — along with their brother Tarek, who they believed was a senior member of Islamic State in Syria, and another man referred to as "the controller" — planned to detonate a bomb on an international flight in July 2017.

When that failed, the group planned a poison gas attack, the court heard.

"The bomb plot ultimately was aborted, the conspirators … the Crown says went as far as to take the brother to the airport with the meat mincer with the bomb inside it … to check into that flight, but [the plan] was aborted at that stage," Mr Crowley told the jury.

"When the young brother went to check the bag in, the bag was too heavy.

"After the bomb plan was aborted at the airport the crown case is that Khaled Khayat was proposing that he take a bomb … but he was counselled by the controller not to do that because he had to stay to do the work here."

Mr Crowley said part of the bomb from the meat mincer was found by police two weeks later in Khaled Khayat's garage, with both of the accused's fingerprints on it.

Police also found instructions on Khaled Khayat's phone for how to produce poisonous gas and how to set it off in a public, confined space, the court heard.

Mr Crowley said the two men were motivated to support militant groups fighting the Syrian regime and to promote Islamic State.

"The Crown case here is those events in Syria vibrated all the way through to the backyards of the accused men, their garages and their homes here in Sydney," Mr Crowley told the court.

"The religion of Islam is not on trial here … two men with their co-conspirators are pursuing a particular strain or view and one which the crown says has [caused them to be] … getting involved in the bomb plot and the poison gas plot."

Mr Crowley told the jury that Khaled had made a range of admissions in his police interviews and "confessed essentially", while Mahmoud denied being involved.

"Mahmoud, when he was interviewed, said he wasn't part of any of these plots — he admitted to doing certain things with Khaled but he wasn't part of a conspiracy," he said.

Mr Crowley quoted a sermon which was on both men's phones in the lead-up to the attempted bomb plot.

He also referred to a message from Khaled to Mahmoud sent on March 6, 2017, describing the death of their nephew in Syria as "martyrdom".

Lawyers for the two accused will deliver their opening to the jury today.