The couple, aged 75 to 80, were found at home around 9:00 pm on Wednesday "already dead, after friends warned of their absence", added the same source.
"A friend of the couple gave the alert for 112 and the GNR went to the location, finding the couple to already be dead, the cause of death is currently unknown, but there is no suspicion of a crime", said the source.
Both victims had British nationality and lived for several years in the area of ??São Bartolomeu de Messines, in Silves, in the district of Faro.
The GNR Silves Criminal Investigation Nucleus is investigating the circumstances in which the deaths occurred, and the bodies were sent to the legal medicine office of Portimão hospital.