Moscow, Jan 17 (Agencies): A long-running probe into the murders of the last Russian Tsar Nicholas II and his family has closed after failing to find evidence that Lenin ordered the killings, the chief investigator said on Monday.

Historians and archivists have found no evidence that the Bolshevik leader or regional official Yakov Sverdlov gave permission for the family to be shot in 1918, Vladimir Solovyov, Russia's chief investigator, told the Izvestia daily.

"The top experts in this subject took part in the investigation, historians and archivists. And I can say with full confidence that on Monday there is no reliable document proving the instigation of Lenin or Sverdlov," in carrying out the killings, he said.

Russia on January 14 closed a criminal probe into the murders after the case was reopened last year on the request of the tsar's descendants, Solovyov said.

Descendants want to prove that the family were victims of political repression, for which investigators have to find evidence that the killings were carried out on state orders, not extra-judicially.

Russia's Supreme Court in October 2008 recognised Nicholas II and his family as victims of political repression but the prosecutor general later ordered the criminal investigation closed in 2009, saying too much time had passed.

In a separate controversy, Solovyov called for the burial of the tsar's two children, Grand Duchess Maria and Tsarevich Alexei, whose bodies are unburied as the Russian Orthodox Church disputes their identification.

Solovyov accused the Church and government of neglecting the remains, and warned they might have to be destroyed.

"Neither the Church nor the state are looking after the remains. I keep the remains of the heir of the great empire and the grand duchess as material evidence," Solovyov said.

The Church has canonised all the members of the last tsar's family, but refuses to recognise the remains of Alexei and Maria, whose bodies were separated from the others and identified by DNA testing in 2008.

Tsar Nicholas II, his German-born wife Alexandra and their five children were shot dead in the cellar of a house in the Urals city of Yekaterinburg on July 17, 1918, after the Russian revolution.