Israel's justice ministry is investigating a hospital that allegedly held a newborn baby as a "guarantee" until a bill was paid.
The ministry intervened last week following reports that East Jerusalem's al-Muqassad hospital held the girl, Israeli press reports say.
The mother, an Israeli citizen, gave birth to triplets two months ago.
The hospital denies keeping the baby and says the triplets were released at different times for medical reasons.
The births were premature and the babies required extensive hospital treatment.
The al-Muqassad hospital is an charitable Arab-run hospital in East Jerusalem.
Because the children's father was a Palestinian resident of the West Bank, the hospital demanded payment of the bill as it was not certain of recovering the costs from the National Insurance Institute (NII), it is alleged.
When the woman said she was unable to pay, the hospital released only two of the babies, keeping the third as a "guarantee", newspaper reports said.
The mother left with just two babies and last week approached the justice ministry.
"We looked into the matter with the hospital," the ministry's head of legal aid, Eyal Globus, told Haaretz newspaper.
"And it turned out that things were exactly as the mother said they were - the third baby was being held there."
Mr Globus was told by the hospital director that this was the normal procedure for ensuring payment.
The ministry ordered the release of the child and said it would ensure the insurance fund reimbursed the hospital, newspaper reports said.
The woman's family told Haaretz that two other Israeli hospitals had turned her away because she could not pay a deposit of $72,500 (£40,000) before being admitted.