Five Muslim men were found guilty on Friday of plotting a violent jihadist attack in Australia using guns and explosives after the country's longest terror trial.

The men, who are facing possible life sentences, showed little reaction to the verdict reached after a 10-month trial. But there were angry scenes outside the purpose-built high-security court as their supporters scuffled with media.

Prosecutors had said the men intended to punish Australia for sending troops to fight in Iraq and Afghanistan. Four others were earlier convicted over the plot hatched between July 2004 and November 2005.

The five were "motivated by a perception that the participation of Australia in the conflicts in Iraq and Afghanistan were acts of aggression against the wider Muslim community," prosecutor Richard Maidment told New South Wales Supreme Court earlier.

The five spent months collecting chemicals, firearms and ammunition, and raids on their homes found "large quantities of literature which supported indiscriminate killing, mass murder and martyrdom in pursuit of violent jihad".

The men, aged 25 to 44, had pictures and videos showing the hijacked aircraft smashing into the World Trade Centre in New York on 11 September, 2001, as well as beheadings and death on the battlefield, Maidment said.

He described all five as devout Muslims who believed Islam was under attack throughout the world and that there was a religious obligation to come to its defence through "the pursuit of violent jihad", or holy war.

This involved "the application of extreme force and violence, involving the killing of those who did not share the extremist belief held by the accused," Maidment said.

The jury was shown more than 3000 exhibits, heard from over 300 witnesses and was taken through numerous intercepted phone calls and text messages during the trial.

Lawyers for the five accused said there were innocent explanations for much of the material and labelled the case "propagandist". The prosecution did not reveal the supposed target for the attack.

Justice Anthony Whealy had urged jurors to put aside any prejudices before beginning their deliberations, which lasted four-and-a-half weeks.

"Special demands have been placed on your concentration. It has been my observation that you have acted with the utmost integrity and diligence," he said on Friday.

"Importantly, I'm sure that you have brought considerable diligence and an amount of integrity to the important task of deliberation."

The verdict angered supporters of the men who were watching live footage on a TV screen outside the court. One man had to be restrained after clashing with two cameramen.

A sentencing hearing was set for 14 December.