The Australian Prime Minister, Tony Abbott, says he regrets that an asylum seeker was given limited access to her sick baby, but believes it happened because the mother tried to come to Australia illegally.
The woman from Myanmar, who is known as Latifa, is an ethnic Rohingyan, which the United Nations says is one of the most persecuted minorities in the world.
She gave birth in a Brisbane hospital last week but was returned to the Nauru detention centre while her baby remained in the neonatal intensive care unit.
Mr Abbott says he deeply regrets she was separated from her child.
But he says he won't apologise for what happens when people come to Australia illegally by boat.
A spokesman for the Immigration Minister Scott Morrison said on Thursday that doctors at the hospital had advised it is common for mothers not to stay overnight because of bed restrictions.
But in a statement, the Mater Hospital suggested Latifa should have been allowed to visit her child whenever she wanted.
ABC news reports Mr Morrison revealed on Friday he has asked his department to investigate the matter.