The corpses belong to a 46-year-old English woman and a 49-year-old man of Swedish nationality.
The corpses were inside a room of Alojamento Local (AL), accommodation normally dedicated to tourism, and which is located in Travessa São Sebastião, next to the Porto Cathedral.
A source from the Judiciary Police told the Lusa agency that "a suspicion of crime has not been confirmed".
A source from the PSP criminal investigation police said, in turn, that there are suspicions of “misuse of psychotropic substances”, which may have led to an overdose.
An official PSP source told Lusa that the alert was given at 1:10 pm on Friday and that a PSP patrol from the area and a team from the PSP's Criminal Investigation Department (DIC) went to the site.