The State Department is "deeply disturbed" by reports that prosecutors raided Azerbaijan's local Radio Free Europe/Radio Liberty office Friday, a US official said, calling the motive for the episode "unclear."
Prosecutors in the tightly-controlled Caucasus nation searched the offices of US-funded Radio Azadliq, confiscating equipment and computers while accompanied by armed police, its director Kenan Aliyev told AFP.
The search was the latest in a string of similar raids on foreign-funded groups in recent months.
"We are deeply disturbed by reports that employees of the RFE/RL bureau in Baku have been detained in their offices and questioned while the premises were searched by police," a senior State Department official said.
"The reasons for the questioning and search are unclear."
Those searching the office whose telephone and Internet lines were cut, said they had a court order to shut it down and forced journalists out, Aliyev said.
The move came after a prominent investigative reporter working for Radio Azadliq, Khadija Ismayilova, was arrested in early December and placed in pre-trial detention for two months.
"We call on the responsible authorities to respect Azerbaijan's international commitment to protecting media freedom," the State Department official said.
"A free and independent press is critical to the wellbeing of the nation."
Non-governmental organisation groups focused on reporter and human rights called the move the latest crackdown against a free media in Azerbaijan, where dissent is often met with a tough government response.
Headquartered in Prague and funded by the US Congress, RFE/RL broadcasts to 21 countries across Eastern Europe, Central Asia and the Middle East.