Ukraine's parliament endorsed on Monday a plan to mobilise 40,000 reservists to counter Russia's "blatant aggression" in Crimea and guard against what a senior official described as further incursions in the south and east of the country.

Andriy Parubiy, Secretary of the National Security and Defence Council, told parliament that 20,000 reservists would be deployed as part of the armed forces and the other half would serve in a newly-created National Guard.

"What has taken place is a seizure, blatant aggression": Andriy Parubiy.

Crimea was brought under Russian control earlier this month and in a referendum held on Sunday, more than 96 percent of voters were officially said to have backed a proposal to secede from Ukraine and become part of Russia.

"What has taken place is a seizure, blatant aggression, the seizure by Russia of parts of the territory of Crimea and the city of Sevastopol," Parubiy told the chamber before the vote.