More than 10,000 people were detained at recent rallies in Russia in support of Kremlin critic Alexei Navalny with many subjected to mistreatment in police custody, monitors said yesterday.  Navalny's supporters took to the streets in cities across the country on consecutive weekends last month calling for his release from detention and denouncing Kremlin rule. Hundreds more filled the streets of the capital Moscow Tuesday evening, after Navalny, 44, was ordered behind bars for nearly three years on old embezzlement charges. At nationwide rallies over the last two weeks, more than 10,000 people were seized by police, the OVD-Info group that monitors opposition protests reported yesterday.