Sydney, Aug 4 (DPA) Police swooped on a suspected Islamic terrorist cell Tuesday in Melbourne to forestall a possible suicide attack on an Australian Army barracks, authorities said.

More than 400 police raided 19 homes and picked up people from the country's 16,000-member Somali refugee community in the biggest anti-terrorism operation in three years.

'We believe these men were affiliated with a group called al-Shabaab in Somalia,' acting Federal Police Chief Commissioner Tony Negus said.

Members of the group, who have been under surveillance since January, had been observed casing Sydney's Holsworthy Barracks and other military installations.

'We were satisfied the timing was right,' Negus said. 'Obviously, the primary concern is public safety.