An Australian Islamic man has told a court in Melbourne he is guilty of being part of a terror cell that plotted to kill thousands of people at major sports events.

Only moments before his retrial, Muslim convert Shane Kent, 33, pleaded guilty to being a member of a terror cell led by radical cleric Abdul Nacer Benbrika.

Kent admitted involvement in the cell's plans to place bombs at a major football event in Melbourne: the Australian Grand Final in 2005, which attracted nearly 100,000 fans and a TV audience of millions.

Kent has been tried once before and was about to face a retrial on charges he had previously denied.

Six other members of the cell, as well as the cleric Benbrika, were last year found guilty on related charges.

Benbrika was jailed for 15 years, but not before he nominated women and children as fair game for terrorists.

He referred to himself as a holy warrior, and said he considered violent jihad to be an important part of his religious obligations.

Material seized from Benbrika and his group included bomb-making instructions and video tapes with messages from al-Qaeda leader Osama bin Laden.

The plot on the football match was discovered after a series of intelligence operations by police and Australia’s secret service.