Last year bone fragments and teeth belonging to two young people were found about 70 metres (77 yards) away from the site where Russia's imperial rulers had been buried.
TEETH AND FILLINGS
Forensic scientists said molar teeth and amalgam fillings found with the new remains matched those found among the remains of the other members of the royal family.
Scull fragments showed injuries consistent with bullet wounds. Numerous genetic tests showed the remains of both groups belonged to one family group.
"The overall scientific results, which were based on DNA tests using three genetic systems, agrees with the hypothesis that in the second burial site the remains of Grand Duchess Maria and Tsarevich Alexei have been found," the Prosecutor-General's Office said in a statement.
Since the collapse of the Soviet Union in 1991, the Kremlin and many Russians have sought to reconnect with their pre-revolutionary past.
President Dmitry Medvedev has said he admires Nicholas II, whom many historians blame for being too weak and setting Russia on a path to civil war and dictatorship.
"His life ended in tragedy but then it began again. That's what we're celebrating today," Nadia Basharova, 50, said as she listened to a priest sing.
The Russian Orthodox church has canonised the Tsar and his family as martyrs.
By mid-morning around 300 people had gathered at the Yekaterinburg church, which is just a 20-minute walk away from a statue of Vladimir Lenin, the architect of the Soviet Union who is blamed by many for the murder of the Tsar and his family.
