The reporter was kidnapped Tuesday evening by "unknown individuals", according to Iraq's interior ministry, which said it had detained one person in relation to the case.

Washington said the suspect was believed to be connected to the US-blacklisted Kataeb Hezbollah group.

The State Department has not named the journalist but she was identified as Shelly Kittleson by media advocacy groups and one of the news outlets she worked for.

The department said it had warned of the security risks and was working to ensure the reporter's release "as soon as possible".

According to a US official who spoke to AFP on condition of anonymity, Kittleson had been contacted repeatedly about threats against her.

The Iraqi security official, also speaking on condition of anonymity due to the sensitivity of the case, confirmed the arrest of "one of the kidnappers".

"He was carrying identification indicating his affiliation with the 45th Brigade of the Popular Mobilisation Forces (PMF), a brigade affiliated with Kataeb Hezbollah," he said.

Iraqi authorities earlier said the man was detained after security forces intercepted a vehicle that overturned as he tried to flee.

The security official told AFP that authorities had "found the kidnapped woman's bags inside the car".

The PMF is a sprawling coalition of armed groups now integrated into Iraq's regular army but which contains pro-Iran factions that have a reputation for acting independently.

The Iraqi official said the arrest took place near Jurf al-Sakhr, a known Kataeb Hezbollah stronghold south of the capital.

Kittleson is a "legitimate journalist" with experience in the Middle East and is usually based in Rome, according to the International Women's Media Foundation.

Baghdad was previously notorious for kidnappings and attempted abductions, but they have decreased as the security situation in Iraq improved in recent years.

Israeli-Russian academic Elizabeth Tsurkov was kidnapped in Baghdad in 2023. She was held for two years until her release last year.