”All flights that are not regular flights are classified under Sweden’s secrecy legislation” confirmed Caroline Karlsson, advisor to minister for infrastructure, Catharina Elmsäter-Svärd.

Denmark, Finland and Norway are among seven countries that have shared their information, while Sweden, Canada and Portugal refuse, according to Access Info Europe, one of the organizations behind the study.

The American Federal Aviation Administration (FAA) has released 27,128 documents to the two organizations, Access Info Europe and Reprieve.

So far, Eurocontrol, the European Organisation for the Safety of Air Navigation, has joined Sweden, Canada and Portugal in refusing to give out any information.

Five countries, including Great Britain, say they don’t have the information requested by the organizations, while 13 countries have so far failed to answer.

One incident when a CIA plane touched down on Swedish soil, receiving significant attention in Swedish media, was the flight transporting Egyptians Mohammad Alzery and Ahmed Agiza from the Bromma airport in Stockholm to Egypt in 2001, where they later were tortured in prison.

Sweden has previously been slammed by human rights organizations about its part in the incident.

The actions of the Swedish security service Säpo has been criticized but the highest authority belonged to Sweden’s foreign minister at the time, Anna Lindh.