The former Spanish colony has emerged from obscurity over the last decade to become Africa's fourth-largest oil producer, largely through U.S. firms, and is now attracting European companies seeking new gas reserves.
"Its government, however, is setting new low standards of political and economic malfeasance," New York-based Human Rights Watch (HRW) said in a report, which the watchdog attributed to four years of research.
"Billions of dollars in oil revenue have not translated into widespread economic benefits for the population or dramatic improvements in human rights, making Equatorial Guinea a classic example of an autocratic and opaque oil-rich state," said HRW.
President Teodoro Obiang Nguema Mbasogo (pictured) has ruled the central African country since 1979.