The victim's dismembered body, which had not yet been identified by Monday morning, was found in a wooden area just outside Calella on Saturday afternoon.
According to Spanish news agency ACN the murder took place at a nearby tourist resort. The body parts are then said to have been transported to the place where they were later found in a bag.
On Sunday Catalan police said they had arrested a Swedish man in his forties, but declined to comment further.
“Unfortunately we don't have the right to give you any kind of details about this case,” a spokesperson at the local police station told Swedish tabloid Aftonbladet late on Sunday.
Calella is a seaside resort on the Costa del Maresme coast, located around 58 kilometres north of Barcelona and popular among Swedish tourists.
According to ACN the murder suspect, who is reported to be in his younger forties, was vacationing in the area.
The Swedish Foreign Ministry was unable to offer any information when approached by media.
“Neither us nor the embassy has any knowledge of any man being held in that area,” Foreign Ministry press officer Emma Karlsson told Swedish newswire TT.
Swedish police said they had not yet been contacted by their Spanish colleagues, but did not rule out that they would offer assistance if required.