"There is no doubt that he is the secret agent 'Thomas'," said diocese lawyer Anna Wernqvist in a Church of Sweden statement following a visit to the Stasi archives in Berlin.
The now 68-year-old man, named by DN as Alexsander Radler, is now known to have spied for the Stasi for 24 years and continued his service after arriving in Sweden in 1968.
Radler now faces being stripped of his licence to preach, the newspaper reported.
Luleå cathedral chapter had previously considered the matter after Radler was implicated in a book by researcher Birgitta Almgren in October 2011. The investigation was however closed due to insufficient evidence.
In discussions with the bishop Radler furthermore flatly denied the allegations forwarded in Almgren's book, which was based on the Swedish Stasi files.
But following further revelations in a report based on the Stasi archives in the Expressen daily in April, the Church of Sweden reopened the case against the pastor.
Anna Wernqvist's visit to Berlin has now confirmed that Alexsander Radler and Stasi spy "Thomas" are one and the same person.
"According to the German authorities there is no doubt whatsoever that the pastor has handed over information to the Stasi," Wernqvist said in the statement.
A key element of the ongoing Church of Sweden investigation will consider the issue of whether Radler has been economical with the truth in contact with the media and church authorities.
As the pastor's action were not illegal under German law at the time, he is however not suspected of any crime.
Furthermore as the 68-year-old is now a pensioner he does not risk losing employment over over his clandestine past, but it is likely that he will be stripped of his pastor's licence.
Wernqvist told DN that it is expected that the church investigation is unlikely to be completed before September.