The man was arrested in absentia earlier this week and taken into police custody Tuesday morning by Swedish police. He remained in custody Tuesday evening.
"There has been an ongoing investigation for a long time against this man," chief prosecutor Tora Holst at the International Public Prosecution Office told the newspaper.
The man is believed to have been involved in the 100-day massacre that began in April 1994 and left some 800,000 dead. He is registered at an address in central Sweden and was born in Rwanda, coming to Sweden in 2002.
Holst declined to say what role the man may have played in the genocide.
Last summer, Sweden convicted and sentenced 54-year-old Swede Stanislas Mbanenande to life imprisonment for participating in massacres of tens of thousands of people in Rwanda in 1994.
His trial was the first ever in Sweden for genocide.