More than 150 people took part in protests at three Scottish airports over allegations they have been used for CIA "prisoner transfer" flights.
Edinburgh Airport was the scene of one of the protests
Scottish Socialist Party MSPs and the Stop the War Coalition were among those at Edinburgh, Glasgow and Prestwick.
The protest came days before an SSP debate at Holyrood on the flights.
Foreign Secretary Jack Straw said there was no evidence America was using UK airports to move CIA terror suspects.
Amnesty International has claimed that planes refuelled in Scotland after transferring detainees to countries where they risked torture.
It said it had information about two flights in 2001 and one in 2002 where planes had landed at Prestwick after taking detainees to Jordan and Egypt.
Sunday's protests were staged by campaigners who want Scottish police to investigate the "rendition" flights.
Socialist MSP Rosie Kane urged First Minister Jack McConnell to ask the US Government whether it has used Scottish territory for extraordinary rendition.
"The Scottish Executive can't hide under the cloak of devolution any longer on this," she said.
"The evidence is mounting that a crime under Scottish and international law has been committed on our soil and so why won't the police and ministers act?
Balloons were released at Glasgow Airport on Sunday
"The people of Scotland don't want to align ourselves with this barbarity."
Scottish National Party justice spokesman Kenny MacAskill said the Scottish Executive had "stood idly by" while prisoners were transported through Scotland.
"This is fundamentally a political and not a police matter, and so it requires a political will to end it," he said.
"Ministers must ensure that Scotland's police forces are in no doubt that they will have the executive's full backing if they intervene to stop this practice now."
The protesters at Edinburgh Airport included 27-year-old postman Robert Lawrence, who was dressed in a Guantanamo Bay-style orange boiler suit with his hands and feet shackled.
Demonstrators released 176 balloons at the three airports to symbolise the number of CIA flights they claim have landed on Scottish soil.
The US has admitted that terror suspects have been flown abroad for interrogation, but denied they were tortured.
The SSP will stage a Scottish Parliament debate on the flights on Thursday.