G4S failed to provide all of the 10,400 contracted guards for the 2012 Games, which forced the British government to step in with military personnel.
The acting secretary to the Immigration Department, Martin Bowles, told a parliamentary hearing that the services to be provided at the processing centre in Papua New Guinea were a “different set of circumstances”.
“I accept it might be the same company, but we are talking about catering, cleaning, security and associated type services,” Mr Bowles said in Canberra on Monday.
“We are not talking about them managing a facility in the same way they may have had a contract with us to manage a detention network a number of years ago.”
Ken Douglas, from the department’s infrastructure division, had earlier told a Senate estimates hearing in Canberra on Monday that a “letter of intent” had been signed with the firm to run the processing centre in PNG.
The department had changed significantly how it managed the detention network in the past 12 to 18 months, Mr Bowles said.
Mr Bowles said he had never noted the system had been “perfect”.
“I said quite often that we are always looking to improve. We will continue to do that,” he said.
Australian authorities have so far transferred 292 asylum seekers to Nauru’s processing centre, while the first transfer to Manus Island is expected in the coming weeks.
Since the government announced its new border protection policies on August 13, 4615 people who had arrived by boat have not had their claims assessed for asylum.