The result is comparable to the drop in assaults in Newcastle after similar changes to liquor laws made in the city in 2008, Bureau of Crime Statistics and Research director Don Weatherburn said.

That was despite Sydney having far more venues and several other entertainment precincts  that weren’t subject to the restrictions, to which revellers could have  drifted.

But researchers found no evidence the introduction of 1.30am lockouts and 3am last drinks in Kings Cross and the CBD last year, which followed the ‘‘one-punch’’ deaths of Sydney teenagers Daniel Christie and Thomas Kelly, had pushed violent punters into other parts of the city.

In a new report, the bureau found assaults in Kings Cross had fallen by 32per cent and were down 40per cent in  Sydney’s CBD since the reforms were implemented, compared to a 9per cent drop   statewide.

The change was ‘‘one of the most dramatic effects I’ve seen in my time of policy interventions to reduce crime’’ and both precincts ‘‘are now much safer than they were’’, Dr Weatherburn said.

But a key issue still being researched is whether the new laws curb drinking in the nightspots or, as pub and club owners claim, simply discourage people from going there.

The measures were borrowed from Newcastle, where similar conditions were initially imposed on 14 hotels in 2008.

Those led to a 37per cent reduction in late-night assaults in the first 18 months.

Further research from the University of Newcastle last year found assaults had remained down by about a third.

Dr Weatherburn said the initial Sydney results were ‘‘comparable in magnitude to the effect in the Newcastle location and that’s somewhat surprising ...  when there’s so many other places that people could have gone,’’ he said.

Health professionals and alcohol campaigners want the restrictions rolled out elsewhere in the state.