Domestic violence in December reached its highest level in 15 years, bucking a statewide decline in all other major offences.

Figures from the NSW Bureau of Crime Statistics and Research show, on average, 94 domestic violence assaults were reported to police each day.

Annual crime data released on Thursday showed a 1.9 per cent rise in domestic violence related assaults in the past five years.

But it is believed up to half of all incidents go unreported.

The bureau's director, Don Weatherburn, said the problem was far worse in regional and rural NSW, where rates of domestic abuse are up to 11 times those of Sydney. In Walgett the rate of domestic violence is eight times the NSW rate. In Moree it is almost four times and in Bourke it is 11.6 times the NSW rate.

Deputy Police Commissioner Nick Kaldas said ''domestic violence is something that we are very focused on, and it's of great concern - particularly in the bush.''

He said a whole-of-government response was the only way to tackle domestic violence.

''The Department of Community Services, health, education and the police are working much closer together than we have in times gone by to try and stop the problem rather than trying to deal with it as purely a law enforcement issue.''