Russia will exhume the remains of Tsar Alexander III as part of a probe into the century-old murder of his son, the country's last emperor Nicholas II, and his family, investigators say.
Russia's powerful investigative committee in September exhumed the remains of Nicholas II and his wife Alexandra in an attempt to resolve a dispute over the identity of remains thought to be those of the couple's children Alexei and Maria.
The royal family and their servants were shot by the Bolsheviks in 1918 after the Russian revolution and thrown into a mineshaft before hastily being burnt and buried in the provincial city of Yekaterinburg.
The remains of the tsar and tsarina were discovered in a mass grave along with those of three of their daughters in 1998 and officially identified seven years later ahead of a reburial in the former imperial capital Saint Petersburg.
A second grave was discovered at a different spot with remains believed to be those of the tsar's heir Alexei and daughter Maria in 2007.
Despite subsequent extensive DNA tests by international scientists showing that all the Romanov remains are authentic, the Russian Orthodox Church does not recognise the identity of Alexei and Maria's remains which are in limbo in state archives.
The Church has declared all the Romanov family saints, which means it must recognise their remains as holy relics.
Criminal investigator Vladimir Solovyov who has worked on the case from the start told Russian news wire Interfax that the decision had been taken to exhume Alexander III, who died in 1894, following a request by the head of the Orthodox Church, Patriarch Kirill.
"At the initiative of Patriarch, the decision has been taken on the opening of the tomb of Tsar Alexander III," Solovyov said.
The tomb is in Saint Petersburg's Peter and Paul cathedral, where Nicholas II and his wife and three daughters are buried.
The question of the authenticity of the remains has taken on fresh urgency ahead of the looming centenary of the murder, as the Russian government wants to bury all seven family members together.
No more details were given on when the exhumation would take place and the investigative committee refused to comment immediately.
The Romanov dynasty ruled Russia for some 300 years before Nicholas II abdicated in 1917 after the Bolshevik Revolution and ensuing Communist rule.
The Soviet authorities portrayed him as weak, vacillating and despotic but he was canonised by the Russian Orthodox Church in 2000 as a martyr.