Opposition parties have stepped up calls for an inquiry into allegations that CIA "prisoner transfer" flights have used Scottish airports.
The US is accused of moving prisoners through Europe
Amnesty International has claimed CIA flights refuelled in Scotland hours after transferring detainees to countries where they risked torture.
The Greens have called for a statement from the Lord Advocate and the SNP wants a European Parliament probe.
Foreign Secretary Jack Straw has dismissed claims of the transfers.
At Holyrood on Thursday, First Minister Jack McConnell acknowledged concerns about the allegations and said anyone with evidence should provide this to police.
He told MSPs: "I must reiterate that for any allegation of a crime on Scottish soil to be substantiated and for any search warrant in particular to be issued, or even for a court to be approached for that, it is vital that the appropriate evidence is given either to Strathclyde Police or one of the other forces or to the Lord Advocate for him to make inquiries."
Amnesty International claimed it had information about two flights in 2001 and one in 2002 where planes had taken detainees to Jordan and Egypt, then landed at Prestwick for refuelling before heading back to the US.
The Foreign Office has said it had no evidence of a request from the US for over-flights or for refuelling of rendition flights.
There are claims transfer flights have used Prestwick
Rosemary Burnett, Scottish spokeswoman for Amnesty International, said: "In lieu of the lack of action on the part of the UK Government, the Scottish Executive should investigate these illegal transfers as a matter of urgency.
"Not to do so is to aid and abet torture."
Scottish National Party Europe spokesman Alyn Smith MEP said: "Sadly the London authorities, Scottish law officers and police seem unwilling to investigate these allegations, though they are legally entitled to.
"We are supporting a Europe-wide investigation with which I hope the relevant authorities in Scotland will co-operate fully."
The Scottish Green Party had written to the Lord Advocate calling on him "to heed the wishes" of the Council of Europe that all member governments commit themselves to establishing the truth about flights over their territories.
It also raised the allegations issued by Amnesty International.
Green co-convener Robin Harper said: "Of course the first minister cannot request a police investigation, but today he implied that the police have no evidence, that simply is not the case.
"If Scotland is to protect the image of being the 'best small country in the world' then we cannot be seen to be complacent in upholding basic human rights enshrined in UN and EU law."
Green MSPs have written to Strathclyde Police and the Northern Constabulary regarding the reported use of Prestwick, Glasgow, Wick and Inverness airports.
They have also written to Fife Constabulary regarding the reported use of RAF Leuchars airport.