Refat Chubarov, head of Crimean Tatars' self-governing national assembly, has been slapped with a five-year entrance ban to Crimea by the peninsula's pro-Russian administration, according to the Crimean News Agency "Crimean Prosecutor-General Natalia Poklonskaya met Chubarov at Ukraine-Crimea border and read him a warning of extremist activity. Later, Chubarov was handed over a note, banning him from entering Crimea for 5 years," the agency reported Saturday.Former chairman of the assembly, Mustafa Dzhemilev, was also reportedly denied entry to the peninsula in early May.Russia annexed Crimea after a disputed referendum held in the peninsula on March 16 following political crisis in Ukraine.The peninsula's 300,000-strong Crimean Tatars largely boycotted the referendum, which was denounced as "illegal" by Ukraine and the West.Crimean Tatars are the native population of Crimea since the Mongol hordes' invasion in the 13th century.