SDLP leader Colum Eastwood has admitted to using drugs in the past.
The Foyle MLA said he had taken cannabis in his younger days, telling the Belfast Telegraph: “Yes I did, and yes I inhaled.”
It came after a series of high-profile British politicians publicly admitted to using drugs.
The string of admissions was sparked by Tory leadership hopeful Michael Gove confessing that he had taken cocaine on a number of occasions over two decades ago.
The Belfast Telegraph approached each of the main party leaders here asking if they had used drugs in the past.
Mr Eastwood (36) was the only one to answer yes.
Arlene Foster (DUP), Michelle O’Neill (Sinn Fein), Naomi Long (Alliance), Robin Swann (UUP) and Jim Allister (TUV) all replied in the negative.
Green Party leader Clare Bailey could not be reached for an answer.
Mr Eastwood, a married father-of-two, confirmed he had used cannabis when younger.
He said the focus of the drugs debate should instead be on its harmful effects on society here.
“While we’re having this conversation, let’s seriously discuss the major problem we have with addiction in communities across the North,” he said.
“We have people forced into despair, their mental health damaged by the impact of drug, alcohol and substance addiction.
“Without an Executive or a Health Minister we’re paralysed and unable to provide the comprehensive care and support that people really suffering in our communities need.
“Let’s, as political leaders, step up to the mark and deliver on an issue that is tearing people, families and communities apart.”
Last weekend Mr Gove admitted he was “fortunate” to avoid prison after using cocaine several times 20 years ago. He said he took the class A drug while working as a journalist.
A series of other Tory leadership hopefuls also admitted to drug use.
International Development Secretary Rory Stewart has already apologised for smoking opium – a class A drug in the UK – at a wedding in Iran 15 years ago.
Boris Johnson, the favourite to succeed Theresa May as Conservative Party leader, was asked about claims he had taken cocaine at university by Marie Claire magazine in 2008.
He replied: “That was when I was 19.”
Andrea Leadsom told the Independent that she “smoked weed at university” but had “never smoked it again since”.
Dominic Raab has previously admitted smoking cannabis, while Foreign Secretary Jeremy Hunt said he had drunk a cannabis lassi while backpacking through India, and Esther McVey said she had tried cannabis when she was “much younger”.
Meanwhile, former Secretary of State Theresa Villiers, who is not running for party leader, confessed to smoking cannabis in her past.
Ms Villiers said she “had about three attempts of cannabis at university, only the last time I managed to inhale and was sick”.
“So I never touched it again and wouldn’t recommend to anyone else,” she added.
She made the admission as a panellist on Thursday’s BBC Question Time during which two Welsh politicians – Plaid Cymru leader Adam Price and Labour MP Stephen Kinnock – admitted to drug-taking in their youth.
Other party leaders here confirmed they had never taken illegal drugs.
Jim Allister said: “No, I have not, but I am addicted to plain speaking. Drugs ruin lives and the current bizarre direction the Tory leadership election has taken does nothing to help solve a problem which has led to countless deaths.”
Mrs Long, the newly-elected MEP, said: “I’ve never taken any illegal substances.
“In fact, I’ve never even smoked a cigarette.
“I’ve lived a rather sheltered life.”
Sinn Fein said: “No. She (Mrs O’Neill) has never used illegal drugs.”
The Ulster Unoinist Party said: “Robin Swann has never taken any illegal drugs.”
And a DUP press officer said: “Arlene Foster has confirmed that she has never taken any illegal drugs.”
Full story is available here.