Russian Tsar's Erotic Letters to Young Mistress Auctioned

They made up a secret French codeword for sex - bingerle. They were careful never to use their real names but signed off affectionately: "With you always".

And during more than a decade of furtive correspondence, Russia's Tsar Alexander II and his young mistress Ekaterina Dolgaroukaya wrote frankly of their desire for one another - and of the pleasures of past and future love-making.

Yesterday some 22 unpublished erotic letters written by the Tsar to the woman he simply called "Katia" - and by her to him - were auctioned in Paris. Christie's sold nine of the letters last night for €10,800 (£7,400).

The letters were among thousands exchanged by the pair, whose passionate affair began in the summer of 1866, when he was a 47-year-old emperor and she was an 18-year-old schoolgirl.

After four years of correspondence, the Tsar installed his young mistress in quarters close to St Petersburg's Winter Palace, with direct access to the imperial apartments through a secret staircase.

It was in this annexe, which they nicknamed "the nest", that Alexander II and Katia frequently embarked on what they referred to as "bingerle" - an activity that led Katia to bear the Tsar four children.

The enamoured pair often wrote to each other several times a day. They systematically numbered their love letters, signing off with the phrase: "With you always".

The letters were in French. But some sexual references were jotted down in Russian.

In 1871 Katia writes: "I saw in your eyes that you wanted to throw yourself at me to forget everything and enjoy our bingerle."

In another 28-page missive she reminds the Tsar that she is pregnant and urges him: "not to dare have any bad ideas and to remain untainted ... for I know you are capable in one moment when you want to make it (bingerle), to forget that you desire only me, and to go and make it (bingerle) with another woman."

The Tsar's 14-year affair with Katia was his last great passion. It followed his wife Empress Maria's decision to terminate sexual relations with her husband on the advice of doctors and following the birth of eight children.

The Tsar - who is better known for his enlightened reforms including the abolition of serfdom - married his mistress in 1880, less than a month after the Tsarina's death.

This morganatic union, however, proved short-lived: the following year a group of anarchists assassinated the Tsar when he stepped from his carriage, blowing off his legs.

Katia fled to Nice, taking their letters with her. The Russian government has already purchased more than 4,000 letters exchanged by the pair following a deal with the Rothschild family, Russian news agencies reported yesterday.