Drug squad detectives have said they are dealing with a hardcore of 150 heroin addicts in Belfast alone, many of whom have a £50-a-day habit that they are feeding through a range of criminality.
While heroin use in Northern Ireland is still relatively low compared to drugs such as cocaine, cannabis or so-called legal highs, the criminality associated with addiction is a cause of concern.
Beat police in the city centre have said the public are reporting sightings of open drug dealing and heroin use in greater numbers.
Those policing the main shopping area have said that while they are able to disrupt the supply of the drug as soon as they arrest a dealer, they're quickly replaced with someone else.
An operation involving uniformed and undercover officers has been running in Belfast since October to crack down on heroin use and supply.
It has resulted in up to 30 arrests for a range of offences including possession with intent to supply the drug.
Police on the ground say that contrary to public perception, the increased use of the drug is not linked to foreign national gangs and there are "as many, if not more home-grown" dealers involved.
Police say that of the 140 major crime gangs operating in Northern Ireland, only single figures would be involved in heroin distribution.
The drug is mainly transported in small amounts by low-level street dealers who travel to Dublin by train or bus, selling it on to addicts at meeting points arranged over the phone.
Detective Inspector Andy Dunlop of the PSNI's reactive and organised crime branch said heroin use, while still not endemic, can be found across Northern Ireland.
"Heroin is used right across Derry/Londonderry, it's in Ballymena - always has been - Belfast, Newry, Dungannon, Cookstown, Enniskillen, it's all over. But it has been all over, that's not new and we are still talking about small numbers.
"The last time we seized kilos of heroin was in 2008, so we're talking ounces.
"But again you're getting five wraps per one gram, that wrap costs £25 typically on the street, so 100 grams of heroin is 500 wraps potentially, more than enough for Northern Ireland in any day.
"The usage or misuse of heroin is significant lower than any other city across the water.
Police have said there are challenges facing officers trying to stop cross-border dealing because of the methods used.
The majority of heroin in Northern Ireland comes from Dublin and is transported by dealers who conceal the drug within their body, often inside plastic eggs.
"The risk of detection is reduced because they've got it in a Kinder egg and they're bringing it up that way, so a quick stop-search of them maybe doesn't recover it because they have it concealed in them and so unless we've the intelligence to justify arresting them it's getting through," Mr Dunlop said
And the senior detective said they were also using the National Crime Agency and civil recovery to disrupt the supply of narcotics by targeting the gang leaders who were profiting.
"They're people who might never have their hand on the actual drugs and so we go after the proceeds of crime instead."
