He understood a complaint had been made to student magazine Critic Te Arohi, but he was unaware of any allegation being made to police.
He had not been arrested. Smith said he had problems with alcohol in the past, but had no memory of being a perpetrator of sexual misconduct.
His statement said he has been made aware of the complaint against him.
"This absolutely wrecks me."
Though not admitting guilt, Smith said he had betrayed people's trust.
He had also been a victim of abuse. "I do not remember any of these instances. I have struggled with alcohol for most of my life ... and was a pretty full-on blacked out alcoholic from 14-19 years of age.
"However, this is no excuse for my actions."
The complaint against Smith followed a survey carried out at the Dunedin Fire and Circus Club that revealed a problematic culture at the club in relation to predatory behaviour.
A review recommended a change of leadership and Smith stood down as president at the start of this month.
"As the president, it was my fault that the channels for reporting this behaviour had not existed beforehand, and for creating spaces that were not safe," he said in his social media statement made before the complaint about his own conduct surfaced.
In the statement he said: "Never in my right mind would I ever bring this type of pain into anyone's life and it breaks my heart a thousand times over that I have done so.
"From this point on I am going to exclude all substances from my life and withdraw from pretty much all social and cultural activities.
"I apologise profusely to those I have harmed, and those whose trust I have broken.
"I guess this is goodbye, for a long while."
Nominations for Smith's replacement as the OUSA clubs representative close today.
Where to get help:
• If it's an emergency and you feel that you or someone else is at risk, call 111.
• If you've ever experienced sexual assault or abuse and need to talk to someone call the confidential crisis helpline Safe to Talk on: 0800 044 334 or text 4334.
• Alternatively contact your local police station.
• If you have been abused, remember it's not your fault.