In a report released on Friday, the rights group said that "a full retrial of the individuals" should be held, "ensuring internationally recognized standards for fair trial are complied with, without recourse to the death penalty", press tv reported.
The report also called on the Bahraini regime to "immediately establish an official moratorium on executions with a view to abolishing the death penalty".
The report came after the supreme criminal court of Bahrain sentenced the three to death and seven others to life in prison on February 26, convicting them of killing three policemen in the village of Daih last year. The court also revoked the citizenship of all 10 defendants.
The amnesty report further noted that during three weeks of interrogation, the defendants "did not have access to their families or lawyers" and, based on their sayings, they had experienced various torture methods, including "being given electric shocks, beaten, burnt with cigarettes, being deprived of sleep, and sexually assaulted".
According to the report, the defense lawyers did not have access to the full evidence against the defendants and were not allowed to cross-examine witnesses. Moreover, the defendants were not given the chance to speak in court.
On Thursday, dozens of anti-regime demonstrators took to the streets in the villages of Daih and Musalla, both located West of the capital, Manama, to denounce the recent death rulings.
The popular uprising in Bahrain began in February 2011. Since then, thousands of protesters have been holding regular mass rallies in the Persian Gulf country.
The protesters are demanding the downfall of the Al Khalifa ruling family and the establishment of a democratically-elected government.