Image copyright PA Image caption The Public Health Agency (PHA) says it is closely monitoring heroin use in Belfast

A service which provides clean needles to drug addicts in Belfast has seen visits to its facility double.

The figures, from the Needle Exchange Programme in Belfast, show an increase in visits from 7,500 in 2012 to just under 15,000.

Because heroin is illegal, it is difficult to get a true picture of the number of users.

There are 18 needle-exchange facilities across Northern Ireland with plans to open three more early next year.

An addict's mother shares her story

A mother from Belfast has told BBC News NI about the moment she learned her 17-year-old daughter had overdosed on heroin.

"It was just after seven at night that I got the call from the Royal to say she had been brought in by ambulance - could I come down," she said.

"It was terrible - I just looked at her and then I texted her daddy and said 'I think you need to be here'. I definitely thought we were going to lose her.

"That night it seemed like there was a wee bit of a breakthrough, because she was crying and telling us that she didn't want to die and that she needed to get off this and she needed help.

Image caption The girl's mother told of her fears that her daughter will "end up dead" from drug abuse

"I wanted to hit her. I wanted to hug her. I wanted to shout at the doctor. I wanted to shout at her - but I just sat there I didn't open my mouth."

The woman said her daughter had been battling mental health issues from the age of 13 and started abusing drugs in her early teens.

"She started to get very aggressive very quickly. She was self-harming. It took over my life from then - I was constantly searching her room for knives," she said.

Her family has struggled to get help for her and her mother says she feels let down by the system.

The girl told her mother that a man injected her with heroin before she learned to do it for herself.

"I just feel numb. I lost my feelings a good couple of years ago now from all the trauma," the mother explained.

"I'm worried that she'll end up dead.

"Everyday I wake up thinking: 'Is this the day we get the call to say that she's dead?"

The Public Health Agency (PHA) says it is closely monitoring heroin use in Belfast.

The Belfast Trust was contacted for a comment on the issue of drug users accessing mental health services but declined to comment.