The US has been ranked sixth with Burma in an annual list of countries that jail journalists, compiled by a New York-based media watchdog.
Al-Jazeera's Sami al-Haj is among those in US detention
The Committee to Protect Journalists listed China as the worst offender, for having jailed 32 journalists last year.
Cuba was ranked second for imprisoning 24 reporters in 2005, followed by Eritrea, Ethiopia and Uzbekistan.
Acting against state interests was listed as the commonest allegation behind the imprisonment of reporters.
Such accusations, including subversion and revealing state secrets, were linked to the cases of 78 out of the 125 journalists imprisoned around the world, according to the report, which was last updated on 1 December.
"We're particularly troubled that the list of the worst abusers now includes Ethiopia and the United States," the Committee to Protect Journalists' executive director, Ann Cooper, said.
"Journalists covering conflict, unrest, corruption, and human rights abuses face a growing risk of incarceration in many countries," she said.
China on top
The report lists six journalists currently in US custody - four of them at detention centres in Iraq and one at the US military prison in Guantanamo Bay, Cuba.
The detainees in Iraq include reporters and cameramen working for Reuters news agency and US broadcaster CBS.
Al-Jazeera reporter Sami al-Haj, a Sudanese national arrested in Afghanistan in 2001, is the only journalist held by the US in Guantanamo Bay, according to the report.
China appeared at the top of the committee's list for the seventh year in a row.
Almost half the reporters jailed in China worked on the internet.
China, Cuba, Eritrea and Ethiopia together accounted for two-thirds of the reporters arrested worldwide, the report said.