Ferrovial is set to take a commanding stake in Broadspectrum, formerly Transfield Services, after its board agreed to a buy-out this week.
Broadspectrum had resisted takeover attempts, but the company's board changed its mind following a PNG Supreme Court ruling that the detention of asylum seekers on Manus Island was unconstitutional.
The PNG Government has said it plans to close the centre on Manus Island following the court ruling, but Broadspectrum is contracted to run the centre on Nauru until 2017.
In announcing a trading halt on Thursday, Broadspectrum said the developments in PNG had increased uncertainty over its contracts with Australia's immigration authorities.
In a statement, Ferrovial says the camps on Manus and Nauru, which the Australian government pays millions for, were not a core reason for the takeover.
"In relation to the provision of services at the regional processing centres in Nauru and Manus Province, these services were not a core part of the valuation and the acquisition rationale of the offer, and it is not a strategic activity in Ferrovial's portfolio," it said.
"Ferrovial's view is that this activity will not form part of its services offering in the future."
(The Manus Asylum Processing Centre. Picture: record.net.au)