Armed men, believed to be Russian soldiers, stand guard outside a Ukrainian military base in Simferopol March 19, 2014. Defying Ukrainian protests and Western sanctions, Russian President Vladimir Putin signed a treaty in Moscow on Tuesday making Crimea part of Russia again, but said he did not plan to seize any other regions of Ukraine. REUTERS/Thomas Peter GENEVA (Reuters) - Russia signaled concern on Wednesday at Estonia's treatment of its large ethnic Russian minority, comparing language policy in the Baltic state with what it said was a call in Ukraine to prevent the use of Russian.

Russia has defended its annexation of Ukraine's Crimea peninsula by arguing it has the right to protect Russian-speakers outside its borders, so the reference to linguistic tensions in another former Soviet republic comes at a highly sensitive moment.

Russia fully supported the protection of the rights of linguistic minorities, a Moscow diplomat told the United Nations Human Rights Council in Geneva, according to a summary of the session issued by the U.N.'s information department.

"Language should not be used to segregate and isolate groups," the diplomat was reported as saying. Russia was "concerned by steps taken in this regard in Estonia as well as in Ukraine," the Moscow envoy was said to have added.

The text of the Russian remarks, echoing long-standing complaints over Estonia's insistence that the large Russian minority in the east of the country should be able to speak Estonian, was not immediately available.

But amid the growing Crimea crisis, Estonia, Latvia and Lithuania - which like Ukraine were all parts of the old Soviet Union - have expressed growing apprehension over Moscow's intentions.

U.S. Vice President Joe Biden is currently in the Lithuanian capital Vilnius as part of a trip to reassure the three countries, all European Union and NATO members, of Washington's support.

Ukraine told the rights council that U.N. experts had found no credible evidence of mistreatment of its Russian minority as alleged by Moscow -- one of whose pro-Kremlin newspapers said this week there was "bloodshed almost like in Syria" in the east of the country.

The new government in Kiev, a Ukrainian envoy declared, was reinvigorating its promotion and protection of the rights of minorities "to the highest international standards".

The envoy asked what measures could be taken to protect Ukrainian, Crimean Tatar and other minority groups in Crimea "whose rights are being violated under the Russian occupation."

Responding, the Russian delegate said there were no violations of minority rights in Crimea and minorities were not being persecuted. The new Russian-backed government there had guaranteed protection of the Tatars.

(Reporting by Robert Evans; Editing by Mark Trevelyan)