By Philippe Laurenson

AIX-EN-PROVENCE, France (Reuters) - Dissident Kazakh oligarch Mukhtar Ablyazov, accused of embezzling up to $6 billion from a bank he ran, went before a judge in southern France on Thursday and could be extradited to Ukraine, court officials said.

"The judge will notify him that he is the object of an extradition request," said a spokesperson for the appeals court in Aix-en-Provence, where Ablyazov was taken after his arrest on Wednesday near Cannes, on the French Riviera.

Ablyazov was arrested under a warrant from Kiev and was thus most likely to be sent to Ukraine, the local prosecutor's office said.

Ablyazov, 50, is accused in Kazakhstan of defrauding BTA bank, and wanted in Russia on fraud and forgery charges connected to the bank's subsidiary. Ukraine was also home to a subsidiary of BTA.

The Kazakh businessman denies the charges, saying they are designed to eliminate him as a rival to President Nursultan Nazarbayev, who has led Kazakhstan for more than two decades with what critics say is an autocratic style.

The French foreign ministry did not immediately confirm any extradition requests for Ablyazov, an outspoken critic of Nazarbayev.

France has signed up to a European extradition convention with some 30 countries that extends to both Russia and Ukraine, but not Kazakhstan. A source close to the matter said the French justice ministry was examining how to proceed.

(Additional reporting by Jean-Francois Rosnoblet in Marseille, Natalie Huet and Alexandria Sage in Paris and Raushan Nurshayeva and Dmitry Solovyov in Astana; Writing by Catherine Bremer)