NSW A-G defends 'tough' terror laws

Radicalised and dangerous offenders in NSW on the brink of being released from jail could be slapped with sentence extensions keeping them behind bars for their entire lives.

If passed, the new terror laws would see criminals locked up beyond their sentences if they're deemed to pose an unacceptable risk of committing further serious terrorism offences.

NSW Attorney-General Mark Speakman introduced the Terrorism (High-Risk Offenders) Bill 2017 on Tuesday and on Wednesday told parliament he made no apologies for how tough the legislation was.

"There's no doubt that laws to keep offenders behind bars after they've completed sentences are tough laws," Mr Speakman said.

"The NSW government makes no apologies for this."

Under the proposed laws, an offender would undergo a rehabilitation review during their time in prison or under supervision, followed by a medical assessment.

They could then be subject to continued detention or extended supervision.

The Supreme Court will be able to make a ruling on a high-risk offender's future within the final 12 months of their detention term.

They can face up to an extra three years in jail or under supervision. Extensions can continue to be made effectively for the rest of the offender's life.

"Unfortunately the people of NSW are all too familiar with the terrible impact caused when the threat of terror manifests itself," Mr Speakman said on Wednesday.

He referred to the tragedy of the 2014 Sydney siege which claimed the lives of two Australians and the several terror plots that have since been stopped by NSW Police.

"One only needs to imagine the carnage that would have been caused if the plot to detonate explosives smuggled on to a passenger plane in a meat grinder had not been foiled by the authorities," he said.

If an offender is deemed to no longer pose an unacceptable risk, and if they've undergone rehabilitation, they won't be subject to extension orders.