Rallies were planned across Ukraine on Sunday as the troubled ex-Soviet state struggled to contain upheaval amid a standoff between Russia and the West over Crimea that shows no sign of easing.
Sunday marks 200 years since the birth of Ukraine's national hero, the poet Taras Shevchenko, and patriotic rallies were planned in Kiev and -- in a show of defiance of Russia's de facto control over Crimea -- the peninsula's key cities of Simferopol and Sevastopol.
Pro-Russian protesters were due to hold a counter-rally in the tense eastern city of Donetsk, where clashes were feared between them and pro-Kiev demonstrators also planning to celebrate Shevchenko.
The internal wrangling over Ukraine's identity and future were mirrored on the international stage by escalating hostilities between Russia and the West.
Pro-Kremlin militia fired warning shots Saturday to stop foreign observers from entering Crimea, and Moscow threatened to suspend its participation in nuclear arms monitoring deals.
It was the third straight day that civilian and military observers from the Organization for Security and Co-operation in Europe (OSCE) tried and failed to enter the Black Sea peninsula to check on the standoff between overpowered Ukrainian troops and a mass of Russian forces and Kremlin-backed militias.
Forty gunmen in balaclavas and military fatigues fired shots above the OSCE convoy of 54 civilian and military observers from 29 of the organisation's member countries.
The OSCE monitoring mission is an instrumental part of a three-pronged diplomatic push by US President Barack Obama that also includes a call for Russia to pull its Crimean troops back to their barracks and Ukraine to hold early presidential polls in May.
Ukraine's border guards service added to the tinderbox atmosphere by reporting that one of its light patrol planes had come under fire from "extremists" in the same area but escaped unscathed.
They also accused Russia of seizing a ferry terminal and a navy yard in the east and southwest of Crimea to send convoys of 67 military transport trucks filled with soldiers toward Simferopol, the capital of the region, whose parliament has voted to secede and hold a March 16 referendum on joining Russia.