At least 10,000 people have been driven from their homes since the start of the Ukraine crisis, with Crimean Tatars the hardest-hit, the UN refugee agency said Tuesday. Crimea's Muslim Tatars, generally seen as pro-Kiev, have fled the southern peninsula in their thousands since a separatist referendum that led Russia to annex the province. Elderly members of the 300,000-strong ethnic group still remember the Kremlin's Soviet-era deportation of Tatars to Siberia. "Displacement in Ukraine started before the March referendum in Crimea and has been rising gradually since," Adrian Edwards, spokesman for the UN high commissioner for refugees, said as he released the figure. "Most of those displaced are ethnic Tatars, although local authorities have also reported a recent rise in registrations of ethnic Ukrainians, Russians and mixed families," he told reporters. The true figure may exceed 10,000, Edwards said, because that number only includes people who have registered with local authorities. Most have stayed in Ukraine rather than seeking refugee status abroad, he said. Last week, a UN human rights probe condemned what it said was the harassment and persecution of the Crimean Tatars, in language that sparked an angry rebuke from Moscow. "Among accounts we're hearing from displaced people is that they have left either because of direct threats or out of fear of insecurity or persecution," said Edwards. "Some report having received personal threats over the phone, via social media, or finding threatening messages left on their property," he said. "People cite fear of persecution because of ethnicity or religious beliefs, or in the cases of journalists, human rights activists and among intellectuals due to their activities or professions. Others say they could no longer keep their businesses open," he added. Edwards said the UN could not say for sure who was responsible for handing out such treatment, nor whether it was part of an organised campaign. - Communities 'exhausted' - Almost half the 10,000 internally displaced people have headed to central Ukraine, and around a quarter to the country's west, a bastion of the movement that pushed pro-Moscow Ukrainian president Viktor Yanukovych from power in February after months of street protests. In the wake of the Crimea takeover, Ukraine is being rocked by fighting pitting government forces against pro-Moscow separatists in the heavily Russified east of the ex-Soviet republic. Edwards said that he did not have separate figures for people fleeing from the east. "The situation in the east is clearly causing displacement," he said. "It's an extremely difficult situation for many people. It is not stable," he added. The UN has set up three offices to help the displaced, in the capital Kiev, the southern city of Kherson, and Lviv in the west. "People are being accommodated in shelters provided by local authorities, or staying in privately owned spaces, such us sanatoriums or hotels. Others are being hosted in private homes," said Edwards. "However the capacity of host communities to support people is fast becoming exhausted," he added.