Police detained 30-year-old Andrei Zamyatnin, working as an assistant at an agricultural university in Uppsala researching plant viruses, on February 15.
The next hearing of the case would take place in two weeks, Sweden's counter-espionage service (SAPO) said.
Earlier, a local newspaper quoted Swedish Chief Prosecutor Tomas Lindstrand as saying that the researcher was being held on suspicion of spying for a certain country, but did not name which one.
Lindstrand did not detail on the scale of damage allegedly caused by the detainee, but said his activities could have a negative effect on Sweden's security and defense capabilities.
SAPO is still refusing to unveil either details of investigation or which country the suspect was allegedly spying for.
On February 21 Russia's Foreign Ministry said in a statement that the spy scandal could affect bilateral relations.
