The man is 26 years old and lives in Florence, media in Italy reported on Wednesday.
The Norwegian man tested positive for coronavirus at a hospital in Florence.
According to Corriere Fiorentino, he has been in hospital with a fever since yesterday but is in good condition. Italian health authorities are retracing his recent movements.
NIPH head of department Frode Forland told Norway’s public service broadcaster NRK that the Norwegian man will remain in care in Italy.
“He is being managed by the Italian health service. Because he is resident in Italy, that is where he will be treated,” Forland said.
The Norwegian health authority said it did not have any information about the man’s reported recent travel to Norway and had not been alerted to this via the prescribed channels.
“If an infection is to be traced in regards to a person in another country, NIPH is informed of this through the (ECDC’s) Early Warning and Response System (EWRS). In this case, Italian authorities would inform NIPH,” Forland said.
Keeping the man in quarantine in Italy, rather than attempting to repatriate him, was the most sensible course of action, he also said.
The number of coronavirus deaths in Italy has continued to creep up, with the twelfth victim confirmed on Wednesday, but the EU has urged people not to panic.
Italy's 12th death occurred in the central Emilia-Romagna region. The victim was a 70-year-old man from Lombardy, the region most affected by the recent surge in the number of coronavirus cases.
All 12 of those who have died so far in Italy were either elderly or had pre-existing medical conditions.
The EU stressed that the outbreak of the novel coronavirus in Europe is concerning but no reason for alarm.
“This is a situation of concern but we must not give in to panic,” EU Health Commissioner Stella Kyriakides told reporters in Rome after meeting Italian Health Minister Roberto Speranza.
No cases have been confirmed within Norway at the current time.