AAP
ASIO is coming under increasing pressure to make public the security assessments of asylum seekers after refusing five Tamils entry.
The secretive agency is tasked with checking the background of all asylum seekers as they arrive at Christmas Island and elsewhere.
Refugee activist Pamela Curr is worried the five who have been knocked back could be stuck in detention for years.
The rising concern was met by a denial from the Department of Immigration that its Christmas Island detention centre was overcrowded.
"The centre is calm and there is good order," a department spokesman, who did not want to be named, said in a statement.
Capacity in the island's centre is 1,832, the department said.
The arrival of 42 more asylum seekers on Wednesday meant 189 asylum seekers had been intercepted in the 13 days of 2010, all part of a $654 million program the government described last year as "the largest surveillance and detection operation against people smuggling in Australian history".
Opposition Customs spokesman Michael Keenan said the growing numbers at Christmas Island would force the government to bring asylum seekers to the mainland and into murky law.
"The government will claim that it won't affect any rights of appeal, however they know full well it is murky legal territory and that is why they have always tried to create the impression that they wanted people processed offshore," Mr Keenan said in a statement.
Ms Curr says it is possible the five Tamils will face a similar fate to two Iraqi men who were held under the Howard government on Nauru for five years before being freed.
"This is an example of where things can go terribly wrong," Ms Curr told ABC Radio, adding that the initial findings should have been made public.
"ASIO operates ... as a secret organisation, beyond the reach of law."
Philip Ruddock was the attorney-general at the time of the Iraqi men's detention.
He offered stoic defence of the need for secrecy when dealing with the ASIO clearances.
"The Australian community would expect that the security organisation should be able to make those judgments unfettered."
The Tamils will remain on Christmas Island until a third country is found to take them as well as two children whose parents are part of the group.