Ukraine is investigating claims that Russia has been distributing passports in the port of Sevastopol, raising fears that the Kremlin could be stoking separatist sentiment in the Crimea as a prelude to possible military intervention.
The allegation has prompted accusations that Russia is using the same tactics employed in the Georgian breakaway regions of Abhkazia and South Ossetia in order to create a pretext for a war.
Russia handed out passports to the residents of the two provinces, which have long looked to Moscow for support, five years ago. The Kremlin has justified its invasion of Georgia in terms of defending its citizens in Abkhazia and South Ossetia from Georgian "aggression".
Mykola Stretovych, an MP with Ukraine`s ruling orange coalition, claimed that Russia was engaged in a massive operation to hand out passports in Sevastopol, home to 400,000 people, many of whom have historic ties with Russia.
Anatoly Gritsenko, chairman of the Ukrainian parliament`s national security committee, launched a probe into the claims which, if true, would represent "a threat to national security", he said.
Tensions between Moscow and Kiev have grown in recent days after Viktor Yushchenko, Ukraine`s pro-western president, imposed restrictions on Russian ships entering the Black Sea Fleet`s base in Sevastopol.
The decision to place limitations on movement to and from the base, which Russia rents from Ukraine, was taken after ships from the Black Sea Fleet were used in military operations in Georgia.
Ukraine further infuriated the Kremlin last week by offering Europe and the United States access to its missile warning systems.
Mr Yushchenko`s alliance with Georgia has caused further resentment among the Crimea`s overwhelmingly Russian-speaking population. The territory was historically part of Russia but was awarded to Soviet Ukraine by Nikita Khrushchev in 1954.
The head of Ukraine`s security service, however, said that despite nationalist tensions in the territory, a rebellion in the Crimea with or without Russian support was inconceivable.
"Prosperity, peace and calm in the Crimea is the very foundation on which the interests of Ukraine and neighbouring Russia coincide," Valentin Nalivaichenko said.
Condoleezza Rice, the US secretary of state, warned Russia that its actions in Georgia would further increase the alienation of Ukraine towards Moscow. Mr Yushchenko has applied for Ukraine`s membership of Nato, a move bitterly opposed by the Kremlin.
"If the Russians intended this as intimidation, they have done nothing but harden the attitudes of the small states around them," she said. "I think the Russians have made a significant mistake here."