The Swedes have also influenced US foreign policy towards the country, Svenska Dagbladet reports.
Last winter relations between Washington and Minsk had hit rock bottom. The Bush government had described Belarusian president Alexander Lukashenko as Europe's last dictator and diplomatic contacts between the two countries had been cut to a minimum.
US foreign secretary Condoleezza Rice then made contact with David Merkel, under-secretary of State for Europe, who recommended Swedish Social Democrat politician Urban Ahlin for the task of diplomatic go-between.
Ahlin had built up an extensive contact network in Belarus and worked with the support of the Swedish government.
Meanwhile within his own party, only leader Mona Sahlin is thought to have known about Ahlin's role in brokering a deal over Kozulin and easing relations between the USA and Belarus, a key Russian ally in Europe.