PREMIER Barry O'Farrell has pledged to lock up as many people and spend as much money as is necessary to conquer alcohol-related violence in Sydney in the toughest law and order measures the state has ever seen.

The announcement - possibly the biggest of Mr O'Farrell's three years in the job - included a significant cultural change to the way the largest city in Australia will be able to consume alcohol.

There will be 1.30am lockouts that will affect a new CBD precinct stretching from Kings Cross to Cockle Bay, the Rocks to Haymarket and over to Darlinghurst.

Last drinks in that area will be served 3am and there will be a 10pm closing time for all bottle shops across the state.

Venues will be able to stay open after 3am but no drinks can be served after that time.

The casinos, small bars with less than 60 patrons, restaurants and tourism accommodation would be exempt.

Under the extraordinary changes announced by the Premier yesterday, those found intoxicated by alcohol or drugs convicted of assault occasioning bodily harm will receive a mandatory minimum sentence of two years.

Those who are intoxicated and commit reckless grievous bodily harm face a minimum of three years, assault against police officers a two-year minimum and affray a four-year minimum.

This is on top of a minimum of eight years for assault occasioning death through so-called "one-punch" crimes to be introduced if the offender is affected by drugs and alcohol.

Sexual assault under the influence will contain a five year minimum, but the irony is there is no minimum sentence for any of the crimes if drugs or alcohol are not involved.

Ralph Kelly, the father of murder victim Thomas Kelly whose killer received just four years' jail over his death yesterday, welcomed the changes saying they had gone "way above what we were asking for".

"Mandatory is the key word here. The judge has no choice now. It's welcome news, very welcome," Mr Kelly said.

But the jail population could swell up to 60 per cent from its current 10,000 with the Bureau of Crime Statistics and Research confirming yesterday that 4088 people were last year convicted of assault occasioning bodily harm and 49 per cent of those offences involved alcohol.

That's before a range of other charges which hundreds are charged with every year that will also be subject to minimum sentences under the changes.

Asked how much he would be prepared to grow the prison population by under the changes, the Premier said: "By whatever it takes to get the message through to people across NSW that it is no longer acceptable to go out drink yourself stupid, take illicit substances, start fights, coward punch people or engage in other assaults thinking you'll get away with it."

"If the judiciary fails to apply the extensive penalties that successive parliaments have given them to deal with serious crime across the community they should not be surprised that governments start to introduce measures like this" the Premier said.

The Premier said that he would spend as much money as it took to accommodate more prisoners and more trials as a result of the changes.

"To keep young people safe and alive, there is no price to be put on it," the Premier said.

Other measures include:

*Free buses to leave every 10 minutes from Kings Cross to the CBD on Friday and Saturday nights.

* A periodic risk-based licensing scheme to be introduced where higher fees are imposed on premises that have later trading hours and poor compliance histories.

* On the spot fines for offensive behaviour and language to rise from $150-$200 to $500 and intoxicated and disorderly behaviour fines to rise from $200 to $1100.

* The maximum sentence for the illegal supply and possession of steroids will be increased from two years to 25 years to bring it in line with Victoria

* The Responsible Service of alcohol online training course will be suspended.

* Voluntary intoxication by drugs or alcohol will be removed as a mitigating factor when courts determine sentences.

* Police will be empowered to conduct drug and alcohol testing where they suspect an offender has committed an alcohol or drug fuelled violent assault.

The announcement came after weeks of accusations of inactions over one-punch deaths in the wake of the murder of teenager Daniel Christie and attack on Michael McEwen.

Parliament will be recalled next Wednesday or Thursday in an attempt to pass the laws.

Shooters MP Robert Borsak said the MPs would support the laws through the upper house but added: "Why doesn't he back our mandatory minimums on gun crime?"

COMMENT: Play-it-safe Premier has come out guns blazin'