The number of domestic violence-related homicides in New South Wales has risen by almost half, prompting police to call on the community to report suspected cases of family abuse.

Key points: NSW police attend about 145,000 domestic violence incidents every year

NSW police attend about 145,000 domestic violence incidents every year 60 per cent of victims have had no previous contact with police

60 per cent of victims have had no previous contact with police Campaign launched to encourage people to report suspected domestic violence cases

There have been 32 homicides related to domestic violence across NSW so far this year, compared with 23 homicides at the same time last year.

Police Commissioner Andrew Scipione said that represents a 40 per cent increase in domestic violence incidents that results in death.

"These are more than just statistics, these are people's lives," Mr Scipione said.

"These are people who are dying in our streets and we need to make sure that we're doing all we can."

Andrew Scipione has renewed his call for people to report cases of domestic violence. ( ABC News: Kathryn Ward )

Mr Scipione added that, in some cases, community members were aware of a history of violence in a home but had reservations about contacting police.

NSW Police attend about 145,000 incidents of domestic violence every year across NSW, or about 400 call-outs every day.

About 60 per cent of those victims have had no previous contact with police.

Assistant Commissioner Mick Fuller said there has been a steady increase in the number of domestic violence incidents reported to police but he said the majority of cases still go unreported.

"People are confident in looking after their neighbours when their car is stolen or their house is broken into," he said.

"But when it comes to matters of domestic and family violence there's still a real feeling that it's a private matter, that it's a matter that should be kept behind closed doors.

"We're really seeking the public to give us that final piece of the puzzle that will allow police to act and perhaps save the next life."

'We just have to start treating it as a crime'

NSW Bureau of Crime Statistics and Research data shows that between June 2015 and June 2016 Blacktown had the highest number of domestic violence related assaults in NSW with 2,014 incidents.

As a proportion of its population, Blacktown ranks 31st of all local government areas in the state for domestic violence assaults.

Over the same period of time, Blacktown also had the highest number of domestic violence related homicides at 5, out of the 34 that occurred across NSW.

A new community service advertising campaign called No Innocent Bystanders has been launched to encourage relatives, friends and neighbours to report cases of suspected domestic violence.

The graphic ads show a neighbour, a friend and a local doctor calling Crimestoppers to anonymously report suspicious bruises on a woman, who is being abused by her husband.

Minister for the Prevention of Domestic Violence, Pru Goward, said there needs to be a cultural shift to encourage bystanders to play an active role in preventing domestic violence.

"It is a crime, we just have to start treating it as a crime," she said.

"If this was your neighbour's car being vandalised you would pick up the phone without a moment's hesitation.

"This is absolutely no different, this is your neighbour being vandalised, this is your neighbour being threatened.

"The more we can do to empower bystanders, family members and friends ... to report their concerns the more chance we have of intervening before it becomes a serious assault or homicide." df

Domestic Violence NSW chief executive Moo Baulch said the campaign reflects a positive shift in attitude within the police force and a wider community response is now required.

"A number of different initiatives are driving a cultural change within New South Wales police, and that's very important, but police can't always be there," she said.

"I think building really strong bystanders, ethical bystander messages, and embedding them throughout our communities is the next step."

Ms Baulch said emphasis on collective responsibility is particularly important for Aboriginal women, who experience disproportionately high rates of domestic violence in NSW.

She said Aboriginal women were 34 times more likely to need hospital treatment due to domestic violence.