Eliasson said that in 2007 he talked twice to Afwerki about Isaak, who has been jailed without charges in Eritrea for seven years, the Swedish newspaper Dagens Nyheter reported Sunday.
The diplomatic efforts produced no success, with the Eritrean president allegedly dismissing Sweden's concerns out of hand, Eliasson said, adding, "(Afwerki) would rather talk about how unjust Eritrea had been treated by the wider world, including Sweden, after the end of the war against Ethiopia."
Swedish ambassador Fredrik Schiller reportedly has made more than a dozen trips to Asmara on Isaak's behalf. But Leif Obrink, the chairman of Dawit Isaak's support association, told Dagens Nyheter that diplomatic pressure isn't working.
"An increasing number of people have begun to realize that quiet diplomacy has reached an impasse and are demanding a tougher approach from the government," he said.
Isaak was arrested in 2001 when Eritrea closed the country's independent newspapers but has never been charged with a crime, advocates say.