Police in New South Wales will be authorized to use lethal force during terrorist sieges under legislation to be introduced to the state parliament.

Premier Gladys Berejiklian says measures providing legal protection for police in these situations will be put before Macquarie Street before month's end.

"As we have seen as recently as this week in Melbourne and on the weekend with the cowardly, evil acts in London, we need to be ever-vigilant to the emerging and evolving risks of terrorism," read the statement from Premier Berejiklian, "NSW will continue to have the toughest counter-terror laws in the country and we will now give our police clear protections if they need to use lethal force against terrorists."

The premier referenced the episode on Monday night in Melbourne during which 29-year-old Yacqub Khayre killed a man, took a hostage, and shot three police officers before cops eventually shot and killed him. 

Under the upcoming law in New South Wales, the police commissioner would have to declare a terrorist incident before officers are authorized to shoot to kill.  "I have to declare a terrorist incident first so it is not any every day power," said NSW Police Commissioner Mick Fuller.

All of this is part of the recommendations coming from the inquest that State Coroner Michael Barnes conducted in the aftermath of the 2014 Lindt Cafe siege in which cafe manager Tori Johnson and Sydney barrister Katrina Dawson were killed by self-styled Islamist gunman Man Haron Monis.  Specialist police stormed the cafe and killed him, but there was a ten minute period during the siege during which police weren't sure if they had the legal authority to take him out.  The new legislation seeks to clarify that.

NSW Police are also planning to upgrade their firepower, equipping public order and riot squad police with military style semi-automatic weapons by the end of the year.