The Human Rights Watch report on Bahrain, home to the US Navy's 5th Fleet, corresponds with accounts of abuse provided by Amnesty International and local activists.
In a statement to The Associated Press, Bahrain's government claimed the country "is unequivocally opposed to mistreatment of any kind," without addressing the specific torture allegations outlined in the report.
Large-scale protests erupted in Western-allied Bahrain in February 2011. Bahraini authorities, backed by security forces from nearby Saudi Arabia and the United Arab Emirates, crushed the rallies, but unrest continues.
The Human Rights Watch report is based on testimony offered by 14 people, who described being physically assaulted while in police or security service custody. Several quoted in the report said they suffered electric shocks and sexual abuse, while others described being hung in painful positions or being exposed to extreme cold, the Associated Press reported.
In one case, a detainee in the report described an officer shoving something under his nose and being told it was "the blood of people who don't cooperate." One said officers beat his genitals with a hose and penetrated him with their fingers. Another told Human Rights Watch that officers threatened to rape his wife.
Human Rights Watch said little has changed since 2011, when the government vowed to grant "no immunity" for anyone suspected of abuses. At that time, King Hamad bin Isa Al Khalifa listened to a report issued by a government-sponsored investigator outlining how his security forces used torture and excessive force to stomp out the demonstrations.
"There have been few prosecutions for abuses relating to the serious and widespread abuses that (the investigators) documented" in 2011, the report said. "The few that have resulted have, almost exclusively, involved low-ranking officers, and have - without exception - resulted in acquittals or disproportionately light sentences."
Meanwhile, the arrests of human rights activists, protesters and suspected militants have continued. In recent weeks, Bahrain increasingly has been stripping convicts of their citizenship. Al Wefaq, Bahrain's largest Shiite opposition group, says at least 199 people have lost their citizenship as "a punitive measure against dissidents."