A Russian pensioner beat his 82-year-old former KGB officer father to death in revenge for the 1918 murder of the country's last tsar and his family, national media said on Monday.

Police say Alexander, a mentally-ill out-patient whose surname has not yet been disclosed, committed the murder after becoming convinced that he was of royal blood.

When discovered by police who were called to the east Moscow flat after a "suspicious noise" was heard, Alexander was reciting poetry proclaiming his royal lineage. He had made no attempt to dispose of his father's dead body.

Tsar Nicholas II, his wife, their four daughters and son, and several servants, were shot dead by the Bolsheviks in a basement in the Urals city of Yekaterinburg in the early hours of July 17, 1918.

MOSCOW, March 1 (RIA Novosti)