Hilary Duff's representatives have denied claims her boyfriend Matthew Koma attacked her neighbour Dieter Addison during a fight about his smoking.

The Younger star took to Instagram on Tuesday (15May18) to accuse Addison of smoking weed through the night and stinking up her home, and reached out to other "New Yorkers with a**hole neighbors" for advice.

She plastered her neighbour's name all over her Instagram Stories, stating: "My neighbour smokes cigarettes and weed all night long. My apartment reeks. Seriously, what do I do?"

On Wednesday, Addison told the New York Post's gossip column Page Six that Koma had assaulted him, however, a representative for Duff contested Addison's retelling of events, telling People.com: "There was no altercation whatsoever. Koma went over today and asked politely yet again for (the neighbour) to take his smoking outside so as not to impact others."

Koma's representative added: "These allegations are untrue."

Addison, who claimed the situation is so bad that he's investigating getting a restraining order against Duff and Koma, is said to have filed a report with the New York Police Department at the scene.

He told Page Six: "I had to call the police this morning because Duff's boyfriend, Matthew Koma, barged in and tried to punch me in the face. I tried to avoid his fist, but he hit me on the head. So I pushed him out of the apartment, but I didn't assault him.

"I have studied martial arts for many years, and I know how to block people. I didn't want a fight. I immediately called my lawyer who told me to call the police."

In addition, sources told the publication that while Addison claims to have called 911 after the alleged fight, the police actually attended to respond to a complaint about someone smoking in a hallway.

Duff's team also expanded on her reasons for making her fight with Addison public, explaining: "Hilary and her young son have been subjected to excessive secondhand smoke, late night noise, garbage in the hallways, and an overall hazardous living environment from this man for months now.

"She tried numerous times in polite ways to handle this situation including countless sessions with the landlords of the building. As every mother knows, protecting your kid has to come first and foremost and that is her primary goal. She reached a breaking point after a 15 hour work day and yet another sleepless night."

The actress has six-year old son Luca with her ex-husband Mike Comrie.