Kyrgyz voters will decide on Sunday whether to become Central Asia's first parliamentary democracy in a referendum that the country's interim leader says is crucial to restoring order after a wave of ethnic bloodshed. More than 250 people were killed this month and hundreds of thousands fled violence between the two main ethnic groups in southern Kyrgyzstan, a former Soviet republic that hosts U.S. and Russian military air bases and shares a border with China, according to Reuters. World powers are anxious that the turmoil does not spread throughout Central Asia, a strategic region rich in oil and gas that is largely run by presidential strongmen and lies on a drug-trafficking route out of Afghanistan. Roza Otunbayeva, a former ambassador to Britain and the United States, leads the interim government that swept to power after President Kurmanbek Bakiyev was deposed in a popular revolt on April 7. The only woman ever to lead a Central Asian republic, she has rejected calls from some in her government to postpone the referendum until simmering violence subsides in the south. The plebiscite is needed to give legitimacy to a government that has never formally been voted in, and paves the way for the Kyrgyz leaders to gain formal diplomatic recognition. Russia and the United States, mindful of their interests in the region, were quick to engage with Otunbayeva -- a fluent English speaker educated in Moscow -- after the April revolt, but neither country has officially recognised her government. "If we allow any delays, this will threaten us with further instability," Otunbayeva said on Tuesday during a visit to inspect the damage in the devastated southern regions. Voters will be asked one simple question: do they approve a new constitution that devolves power from the president to the prime minister? Under the new charter, Otunbayeva would remain interim president until the end of 2011, before stepping aside. Parliamentary elections would be held every five years and the president limited to a single six-year term in office. PROBLEMS IN THE SOUTH Frequent television advertisments remind residents in the capital Bishkek of the June 27 polling day. Voters can also find the draft constitution on the interim government's website. But in parts of the south, separated from Bishkek by a range of snowcapped mountains, administering the vote to a divided and frightened population could be Otunbayeva's biggest challenge. The clashes have deepened divisions between the Kyrgyz and Uzbeks who have a roughly equal share of the population in the south. Many Uzbeks are blockaded inside their neighbourhoods of Osh, the epicentre of the violence, too afraid to emerge. Many are also loath to support what they see as a Kyrgyz initiative, while there is also opposition from some ethnic Kyrgyz residents of the south, the political and family stronghold of ousted president Bakiyev. The interim government has accused supporters of Bakiyev of fomenting the latest violence in the south, which began with a series of coordinated attacks by unidentified individuals. Bakiyev, in exile in Belarus, has denied any involvement. A school in Osh that was to be used as a polling station was burned to the ground, while six ethnic Uzbek officials working for the election commission were detained briefly by unidentified captors on Wednesday evening.