The Irish Council for Civil Liberties (ICCL) says the Government should not simply accept US assurances that prisoners are not being transported illegally through Ireland.
The council was commenting as Minister for Foreign Affairs Dermot Ahern prepares to give evidence to a European Parliament committee investigating the CIA's controversial rendition scheme.
At least 147 flights involved in the programme have passed through Irish airports in recent years.
However, the Irish Government says it accepts US assurances that no detainees have been on board any of the aircraft while they were passing through Ireland.
The ICCL says this is not good enough and the Government should instead set up a regime of random inspections to ensure the US authorities are telling the truth.