Almost 90 years after Nicholas II, Russia's last Tsar, was executed with his family, his self-proclaimed heirs say they have documentary proof that he was murdered on the explicit orders of the Bolshevik government.

Descendants of the Romanov dynasty say papers in the archives of the modern-day Russian government show that the killing deserves to be classed as an act of "political repression", and that Nicholas should therefore be officially rehabilitated.

The Tsar, who stepped down in 1917 as revolution swept Russia, was executed by a Bolshevik firing squad with his family in the basement of a merchant's house in the city of Yekaterinburg on 17 July 1918. His purported remains and those of his wife and three of his five children, were found in 1991 and laid to rest in St Petersburg's Peter and Paul Fortress in 1998.