THE father of a teenager who spent 10 hours with a bomb chained around her neck has revealed he might not have called police if he had realised it was an attempted extortion.

Australian businessman Bill Pulver said he might have paid the ransom rather than call the police to avoid risking his daughter's safety. Neither knew at the time the bomb was fake.

Mr Pulver spoke outside New South Wales state District Court, where investment banker Paul Peters, 52, appeared for a sentencing hearing after pleading guilty to break- ing into the Pulver mansion in Sydney and attaching the bomb. He faces up to 20 years in prison.

"If I had known there was an extortion letter, I ask myself the question: Would I have actually rung the police?" Mr Pulver said. "I'm really not sure what I would have done."

Peters admitted to entering the mansion wearing a ski mask and wielding a baseball bat on August 3, 2011, before tying the fake device to Madeleine Pulver, then 18, who had been home studying for exams.

She phoned her father after Peters left, and he raised the alarm, sparking a bomb squad operation.

Peters fled to the US and was arrested nearly two weeks later.

Two psychiatrists gave differing opinions on Peters' mental state at the time of the incident.