(CNN) -- The head of the Kyrgyz interim government has arrived in the troubled southern city of Osh to participate in Sunday's referendum on the constitution, a government official said Saturday.
"Roza Otunbayeva will vote on Sunday in one of the regions of Osh," government official Roza Daudova told reporters, according to the Russian state-run news agency Ria Novosti.
Kyrgyz citizens can vote from wherever they may be on Sunday, a decision intended to ensure that the hundreds of thousands of people who were displaced early this month in clashes between ethnic Kyrgyz and minority Uzbeks in Osh and neighboring Jalalabad can participate, Daudova said.
Otunbayeva said Friday that some 170 international observers will monitor Sunday's referendum.
Another government official said Saturday that about 7,500 police officers and 7,500 volunteers were being deployed to ensure security during the vote.
Sunday will mark the country's first election since President Kurmanbek Bakiyev was ousted in April. Voters will decide whether to approve the draft constitution, which proposes curtailing the president's powers and converting Kyrgyzstan into a parliamentary republic.
Voters will also decide whether to endorse Otunbayeva as president until the end of next year. She will not be entitled to run for president in elections slated for October 2011.
Whoever wins next year's election would take office in January 2012.
The official death toll in the clashes that began June 10 stands at 275, though government officials say the true figure could be much higher. More than half a million people -- about a tenth of the nation's total population -- were displaced, many taking refuge in neighboring Uzbekistan, and more than 1,300 houses were burned, the agency said.
More than 75,000 refugees have returned to Kyrgyzstan, the Kyrgyz news agency AKI Press reported Saturday, quoting the Kyrgyz border service vice chief.
During a meeting with the secretary general of the Collective Security Treaty Organization, Interim Defense Minister Ismail Isakov said that nearly all the refugees who fled across the border to neighboring Uzbekistan have returned to their homes in Kyrgyzstan, according to Ria Novosti.
On Wednesday, Otunbayeva signed a decree allowing those who lost their identification documents during the events in Osh and its surrounding regions to vote in the referendum.
On Thursday, regional authorities in Osh and Jalalabad began issuing new identification cards to those who had lost documents during the unrest.
Meanwhile, the Russian state-run news agency Itar-Tass reported Saturday that the curfew in Osh and surrounding region had been lifted earlier in the day. But checkpoints manned by police -- without support from the army -- remain in place and the police will remain on alert, it said.
Otunbayeva said Friday that the curfew in Osh could be re-imposed after Sunday's referendum.
The U.S. Embassy in the capital city of Bishbek urged U.S. citizens in Kyrgyzstan to fill their gas tanks, charge their cell phones, stay close to their homes, "keep a low profile," and keep an emergency kit available during the voting.