The Girls Aloud singer made a police complaint following the incident, which occurred on a skiing holiday in Austria, and left Harding bruised and sporting a bandage on her left hand, reports The Sun.
The alleged bust-up occurred on New Year's Eve, when an "almighty row" apparently broke out between the pair.
"There was banging and screaming and a few guests came out into the corridor," a supposed guest in Harding's hotel claimed. "It sounded like a terrible fight.
"By the early hours people had had enough and someone called the police. It was obviously a very serious tiff indeed. There was a lot of screaming and shouting."
The 30-year-old underwent a month-long stint in rehab following her split with fiancé Tom Crane and her subsequent descent into alcoholism and depression.