The alleged victim reportedly suffered fractures and required surgery.
Smith, nicknamed Beefy, had been due to make a comeback fight against local fighter Ilaru Kujala in Finland on 4 September.
However, he withdrew from the fight a few days earlier after suffering a calf injury, according to reports.
Smith has fought at the highest levels, including against elite champions such as Saul ‘Canelo’ Alvarez.
More recently he fought British rival Chris Eubank Jr in two memorable bouts, defeating the Brighton man in the first fight in January 2023 before suffering a defeat in the rematch eight months later.