The two men and two women in question, who were detained on Sunday, reportedly while taking photos of a tunnel leading to an underground military facility, told police that they were tourists, the Czech Television said.
The Czech Foreign Ministry said on Sunday that it had been informed of the incident by Albania, but had not been contacted by any of the four detained individuals.
According to Albanian media reports, nothing illegal was found during the inspection of the four detainees.
Earlier on Sunday, Albanian media reported that two Russian citizens, 33-year-old Svetlana Timofeyeva and 23-year-old Mikhail Zorin, were detained in Albania for allegedly breaching a weapons factory in Gramsh. They reportedly told the police they were photographers and bloggers who document abandoned military facilities.
There was reportedly another young man with a Ukrainian passport among those detained, but his identity remains unknown.
The Russian Embassy in Albania told Sputnik that it had not received any information from the Albanian authorities regarding the alleged detention of Russian citizens in Gramsh, and had only seen information about the alleged incident in Albanian media.