Romelu Lukaku and Ashley Young are among Inter Milan players facing sanctions for a get-together in contravention of Italy's Covid-19 legislation.
Lukaku's entourage said that he went out with some friends to celebrate his 28th birthday but did not organise a party, according to Sky in Italy.
Milan police attended a hotel in the centre of the city in the early hours of Thursday morning and found some 24 people in a restaurant.
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Inter team-mates Achraf Hakimi and Ivan Perisic are also reported to have been with Lukaku.
Regulations in Milan, which is in one of Italy's Yellow Zones, include a curfew between 10pm and 5am with breaches resulting in fines.
Lukaku had scored a last-minute goal in Inter's 3-1 home win over Roma a few hours before the party.
Sky in Italy understands the players involved will not face any additional fines from the club.
Inter were crowned Serie A champions earlier this month, ending Juventus' nine-year dominance and clinching their first top-flight title in 11 years.