A US-based human rights group has accused the Egyptian government of using torture and false confessions in a high-profile anti-terrorism case.
Emergency rule gives state security sweeping powers of detention
Twenty-two alleged members of an unknown Islamist group, the Victorious Sect, were accused of planning attacks on tourism sites and gas pipelines.
Human Rights Watch says its research suggests the security forces may have fabricated the group's name.
It reports claims the case was used to justify renewing emergency laws.
Although the state prosecutor dismissed the charges against the suspects, 10 of them are still believed to be in detention.
The BBC's Ian Pannell in Cairo says this is just the latest in a run of accusations by human rights organisations against Egypt's police and state security apparatus.
The Egyptian government has consistently denied that torture is used routinely and rejected what it sees as foreign interference in its own affairs.
'Pattern of abuse'
The authorities' claims made headlines in April 2006 when they said they had smashed a previously unheard-of terrorist group plotting a series of attacks against soft targets including tourists and Coptic Christian clerics.
"Beyond coerced confessions, there appears to be no compelling evidence to support the government's dramatic claims," HRW says.
"Indeed, it appears that SSI (state security investigations) may have fabricated the allegations made against at least some and possibly all of them," its report says.
Detainees quoted by HRW said they had been beaten and kicked by their interrogators, and some were given electric shocks on their bodies, including their genitals.
Most of the testimonies in the report come via third parties, as the detainees themselves were unwilling to talk directly to investigators, for fear of retribution, HRW says.
A spokesperson for the organisation said the case was not unusual, but was part of a pattern of detention and torture by the Egyptian security services in order to obtain false confessions.
The "Victorious Sect" arrests came to light shortly before Egypt renewed its enduring and controversial emergency laws, which give sweeping powers of detention to the security forces.
"State security needs to show that it's working, that it's useful, and cases like these are useful politically, around the renewal of the emergency law," lawyer Muhammad Hashim is quoted as saying in the HRW report.
The group says the Egyptian authorities ignored requests for information about the case and there was no immediate response to publication of the report.
Earlier this year, another human rights group released a highly critical report on Egypt's record on torture and illegal detention.