"We do not have any credible evidence of issues that would justify concerns on the part of the Russian-speaking population of Ukraine," said senior UN human rights official Gianni Magazzeni, releasing a report on two monitoring missions there.
Since February's ouster of pro-Moscow Ukrainian leader Viktor Yanukovych after months of popular protests, the Kremlin repeatedly has accused Kiev of violating the rights of the ethnic Russian minority, and used this to justify its annexation of Crimea in March.
Attention is now focused on Ukraine's Russified south and east, with a stand-off between separatist militants leading the pro-Western Kiev government to launch what it calls an anti-terrorist operation.
Ukraine has accused Russia of sending in barely-disguised special forces to lead the militants, while Moscow, far more powerful militarily, has warned Kiev against a crackdown and says the country is close to civil war.
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But "while there were some attacks against the ethnic Russian community, these were neither systematic nor widespread", it said, also pointing to allegations that trouble was being stoked by outsiders, including from Russia.
"The situation in Ukraine is not such that would justify action from any one country," said Magazzeni.
Russia and pro-Moscow figures in Ukraine have played up the role of far-right groups in the anti-Yanukovych protests, some of which glorify World War II-era Ukrainian Nazi collaborators.
The report said fears of the far right were "disproportionate" and had been used "systematically used to create a climate of fear and insecurity" in Crimea, with Moscow sending troops, paving the way for last month's annexation after a separatist referendum condemned by the international community.