On Monday British police announced they had arrested seven other suspects - including five doctors or other medical staff in their late 20s - who they said were being held in connection with the three attempted car bombings.
Ruddock declined to reveal the man's identity, destination or nationality, but said he had residency status in Australia.
Two men rammed a burning vehicle into
Glasgow airport on Saturday [AFP]
No charges have been filed yet.
Under Australian federal counter-terrorism laws, terror suspects can be held without charge for three days, and for longer periods with court approval.
The man had been working as a medical registrar at the Gold Coast hospital in eastern Queensland state.
Ruddock did not say what the man's alleged involvement in the British plots was, or whether other people in Australia were under investigation.
Mick Keelty, the Australian federal police commissioner, said the suspect had not been on any Australian intelligence watch lists before a tip-off by British authorities.
No heightened alert
Peter Beattie, Queensland's premier, said police were also interviewing a second doctor - also was recruited from Liverpool – in the case.
Ruddock and Beattie said "a number" of search warrants" had been issued and executed in the area around Brisbane.
But the authorities were keen to stress that despite the arrest and searches, the terror threat against Australia had not been heightened.
"While these matters are obviously of concern, there is no information that suggests the terror alert at medium should be varied," Ruddock said.