"It has been established that the remains belong to a boy of about 12-14 years of age and a 17-19-year-old girl," Vladimir Markin said.
He added that DNA analysis has been conducted in Russia and the United States.
"The results of the examination are being assessed by investigators and will be made public in the second half of July," he said.
Archaeologists said earlier they plan to resume excavations this summer.
The remains of a boy and a young woman were exhumed near Yekaterinburg, where Tsar Nicholas II, his wife, their four daughters and son, and several servants, were shot by the Bolsheviks in 1918. They are believed to belong to Nicholas II's son and heir Alexis, and his daughter Maria.
The tsar and his family members' remains were also discovered near Yekaterinburg in 1991. They were authenticated and buried in the St. Peter and Paul Cathedral in St. Petersburg in 1998, although the forensic results have since been challenged.
The Russian Orthodox Church, which has canonized the murdered Romanov family, called the 1998 burial "a political show."
