Archaeologists in Russia are claiming to have discovered the remains for two of the children of the last Russian tsar almost 90 years after they were shot by the Bolsheviks.

Found near the city of Yekaterinburg, in the Sverdlovsk region of the Urals, where they were being held when they died, experts believe that the remains are those of the crown prince, Tsarevich Alexei, and his sister Maria, son and daughter of Tsar Nicholas II.

However, the discovery has been controversial, restarting the debate about what happened to the last of the famous Romanov dynasty, killed by firing squad in 1918 after the Communists seized power in 1917.

Prosecutors are reported to have reopened the investigation into the final hours and the shooting of Russia's first family, including the deaths of haemophiliac Alexei, heir to the Russian throne, and one of his four sisters, the Grand Duchess Maria.

Forensic experts are examining the remains, which include bone fragments, teeth, bullets and part of a dress. The burial site itself was discovered because of a report by lead executioner to local Communist bosses in 1934.

The missing bodies from the Romanov family has led many people to claim to be lost Romanovs. In 1998, the Tsar and several members of his family received a burial in the imperial crypt at the St Peter and Paul Cathedral in St Petersburg to mark the 80th anniversary of their deaths.