Cape Breton Regional Police are investigating a suspicious death after the body of a 35-year-old man was found last night in Sydney.

Staff Sgt. Reg Hutchings says police were called to a five-unit apartment building on Townsend Street just before midnight.

"Upon arrival we were met by EHS paramedics who had tried to revive a (35-year-old) victim, as a result they were not able to revive the victim," said Hutchings.

"We had some concerns surrounding the death. As a result of that our major crime unit and our (Forensic Identification Service) units have been called out to assist the patrol section in regards to this investigation."

Police are not releasing the name of the victim.

A friend of the victim who lives next door, who would only identify himself as Paul, says he has known the man for two and a half years.

Paul says the victim didn't live in the apartment, but was visiting someone there. He says he saw him earlier last night and says, "He was fine."

"Well last night he was at my house at 7 o'clock and then I went back over to see him for a minute," he said. "He didn't answer the door and an hour or something later, the ambulance came barrelling down... the road. We come over here and found out he was dead."

Paul says the victim is from North Sydney.

Police say the cause of death is not known at this time. They are hoping after an autopsy is performed in Halifax, more information will be provided on the cause of death.

Police say the apartment house where the victim was found is known to police.