An Italian journalist has been under arrest in Iran for more than a week, Italy's foreign ministry has said.
Cecilia Sala works for Il Foglio newspaper and for podcast company Chora Media.
The foreign ministry said it was following Ms Sala's case with "utmost attention" since she was detained by Tehran police on 19 December.
There was no immediate confirmation of the arrest by Iranian officials.
Chora Media said in a separate statement that Ms Sala was being held in solitary confinement at the Evin prison in Tehran and that no reason had been given for her arrest.
Italy's foreign ministry revealed that Rome's ambassador to Tehran, Paola Amadei, had paid her a visit to check on the conditions in which she was being held, adding that she had been allowed to make two phone calls to her family.
It also said Italy "has been working with Iranian authorities to clarify Cecilia Sala's legal situation".
According to Chora Media, Ms Sala left Rome for Iran on 12 December with a valid journalist visa and had carried out several interviews, producing three episodes of her "Stories" podcast.
It added that she had been due to fly back to Rome on 20 December, but her phone went "silent" after she exchanged a few messages on 19 December.
Sala's other employer, Il Foglio, has called for her release, saying "journalism is not a crime".
"Cecilia was in Iran, with a regular visa, to report on a country she knows and loves, a country in which information is suffocated by repression," the newspaper said in a statement on its website.
Last week, Iran summoned the Swiss ambassador in Tehran and a senior Italian diplomat over the arrest of two Iranian nationals, Reuters reported, citing Iranian media.
Iran was rocked by protests in 2022 after the death of 22-year-old Mahsa Amini in September of that year. Tens of thousands of people were arrested in connection with the "Woman, Life, Freedom" protests.
Mahsa had been arrested for allegedly breaking Iranian laws that require women to wear the hijab and she died in police custody.