MORE jails will be built to cope with a hefty increase of prisoners as a result of new mandatory minimum sentences, Premier Barry O'Farrell said yesterday.

Mr O'Farrell's comments come after the government has downsized Grafton jail and shut Parramatta, Kirkconnell and Berrima to combat costs.

Asked how much he would be prepared to grow the prison population 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 offenders are intoxicated, mandatory minimum sentences will be two years for assault and up to four years for reckless grievous bodily harm - and an extra year if they are in company.

But the jail population could swell up to 60 per cent from its current 10,000.

The number of people found guilty in the year to September 2013 for assault occasioning actual bodily harm was 4088 (of which 49 per cent were alcohol affected), 203 were convicted of assault occasioning actual bodily harm in company, 923 were convicted of assaulting an officer in execution of duty, 407 with reckless wounding in company, reckless wounding or reckless grievous bodily harm.

IT was wrongly reported in this story that the NSW Bureau of Crime Statistics and Research predicted that the state government's proposed mandatory minimum sentencing laws would lead to a 60 per cent increase in the prison population.

This was an error that occurred in production. The 60 per cent extrapolation was calculated by The Daily Telegraph. BOCSAR simply stated that there were 4088 offences of assault occasioning bodily harm a year.

SENTENCING REFORMS

ASSAULT

Current Maximum: 5 years. New Maximum: 7 years. New Minimum Mandatory: 2 years

RECKLESS GRIEVOUS BODILY HARM

Current Maximum: 10 years. New Maximum: 12 years. New Minimum Mandatory: 4 years

RECKLESS WOUNDING

Current Maximum: 7 years. New Maximum: 9 years. New Minimum Mandatory: 3 years

ASSAULT AGAINST POLICE OFFICERS IN THE EXECUTION OF DUTY (not during public disorder)

Current Maximum: 5 years. New Maximum: 7 years. New Minimum Mandatory: 2 years

AFFRAY

Current Maximum: 10 years. New Maximum: 12 years. New Minimum Mandatory: 4 years