MOSCOW -- President Vladimir Putin on Wednesday ordered massive exercises involving most military units in western Russia amid tensions in Ukraine.

Defence Minister Sergei Shoigu said in a televised statement made at a meeting of top military brass in Moscow that the exercise is intended to "checks the troops' readiness for action in crisis situations that threaten the nation's military security."

In remarks carried by Russian news agencies, Shoigu said that the manoeuvres involve some 150,000 troops, 880 tanks, 90 aircraft and 80 navy ships.

He said the exercise is unrelated to the developments in Ukraine, where tensions remain high following the toppling of Russia-backed President Viktor Yanukovych.

But Shoigu added that the exercise will be held near Russian borders, including the border with Ukraine. He also said, according to Russian news reports, that his ministry will take steps to strengthen security of the facilities of the Russian Black Sea Fleet in Ukraine's Crimean Peninsula, without elaborating.

The manoeuvres follow a series of war games Russia has held recently. In July, a military exercise in Siberia and the far eastern region involved 160,000 troops and about 5,000 tanks and other armoured vehicles along with the air force and the navy.

Shoigu said the manoeuvres will start Friday and will last four days. The exercise will involve ships of the Baltic and the Northern Fleets and the air force.

Russia has questioned the legitimacy of the new Ukrainian authorities and accused them of failing to control radicals who threaten the Russia-speaking population in Ukraine's east and south.

A senior Russian lawmaker on Tuesday told pro-Russia activists in Crimea that Moscow will protect them if their lives are in danger.