Iraqi militants have released a French-American reporter abducted last week while the whereabouts of three other Western journalists remains a mystery.
Garen earlier reported on Iraqi civilian deaths in Nasiriya
Micah Garen, who was seized along with his interpreter on 13 August in Nasiriya,
told an Arabic TV channel he had been taking photos at the time.
"There was a misunderstanding," he said from the mainly Shia southern city.
A search is still on for two French reporters and an Italian who went missing on Thursday.
Mr Garen and his interpreter, Amir Doushi, were taken to the office of radical Shia cleric Moqtada Sadr in Nasiriya ahead of being handed over to Iraqi government officials.
The journalist, who is the founder of US company Four Corners Media, told al-Jazeera TV he was "very thankful" to the cleric and his aides for helping to secure his release.
Enzo Baldoni (Italian, Diario magazine) - driver found dead near Najaf
George Malbrunot (French, Le Figaro)
Christian Chesnot (French, Radio France Internationale)
All three missing since 19 August
He said he had been captured at a city market where he had been taking pictures with a small camera.
"I think that they did not like it when I was taking some photos," he said.
"There were many people in the marketplace. I cannot tell who they are... I think they considered me to be a suspicious person and, therefore, there was a misunderstanding."
A Sadr spokesman in the city, Aws al-Khafaji, told al-Jazeera that Mr Garen's abductors - whom he only described as "groups" - had approached his office after realising that the journalist had worked to "uncover the truth about events in Iraq, especially in Nasiriya".
As of Sunday, there was still no word on the whereabouts of the other two French reporters, Georges Malbrunot and Christian Chesnot, or Italy's Enzo Baldoni.
The French news agency AFP reports that the two Frenchmen, who are Iraq specialists and were working together, were staying in the same Baghdad hotel as Mr Garen.
UK journalist James Brandon, who was briefly held captive in the southern city of Basra this month, also reportedly stayed at the Al-Dulaimi Hotel in the city centre before travelling south.
The hotel's owner told AFP he was confident there was no connection between the abductions and his hotel, where most of the staff are Shia Muslims.
However, the French consulate has advised all French guests to move out as a precautionary measure, the French news agency adds.
"That's it - there's no way I'm staying here," a French photographer, Jerome Sassini, said as he packed his belongings in his room.