Saudi Arabia saw a number of high-profile attacks between 2003 and 2006
Amnesty International has strongly criticised Saudi Arabia over abuses allegedly committed as part of its counter-terrorism operations.
In a report, the human rights group says since 2001 thousands of Saudi suspects have been detained for years without charge or trial.
The 69-page report describes Saudi Arabia's human rights record as "shocking" and "dire".
It says the international community has been far too quiet about the abuse.
In the report, entitled "Saudi Arabia: assaulting human rights in the name of counter-terrorism", the UK-based organisation accuses the oil-rich conservative kingdom of massive and widespread abuse.
It says that two years ago, the Saudi interior minister said the country had detained 9,000 security suspects since 2001, and 3,106 were still being held.
AMNESTY REPORT ALLEGATIONS
Thousands of people detained arbitrarily
Some of those held are prisoners of conscience
Abuses include beatings, suspension from ceiling, electric shocks
But, says Amnesty International, no information - not even their names and the charges - were forthcoming and unofficial sources put the numbers far higher.
Over the last two years, it says, "new waves of arrests" have been reported.
BBC security correspondent Frank Gardner says the Saudi authorities have been widely credited with defeating al-Qaeda in their country.
And, he says, Amnesty International concedes that most of the thousands detained without trial are suspected of links to groups which have committed attacks, on westerners and other targets.
But it says their cases are shrouded in secrecy and, quoting numerous examples, it doubts that even basic human rights standards are being met.
The director of Amnesty's UK office, Kate Allen, said that, except for the re-education programme for ex-jihadists, and the carefully co-ordinated mass trials, Saudi Arabia's habitual cloak of secrecy was wrapped even more tightly than ever in "security" cases.
"It is true", she said, "that Saudi Arabia faces a challenge in dealing with terrorism, but its response has been shocking - something the international community has been far too muted about.
"We are calling for a fundamental change of policy by the Saudi authorities."
This is not the first time Saudi Arabia has been criticised for alleged human rights abuses.
In February, the US-based organisation Human Rights Watch listed what it called "ongoing serious violations of rights" in the kingdom.
They included restrictions on speech, association, assembly and religion; an arbitrary criminal justice system, discrimination against women; and serious abuses against migrant workers in the country.
And in 2008, it published a 144-page report criticising Saudi Arabia's criminal justice system.
It said that it had "found systematic and multiple violations of defendants' rights".