Russia on Thursday test-launched several ballistic missiles during planned exercises overseen by President Vladimir Putin, news reports said, as a crisis raged in neighbouring Ukraine.

The Russian military fired a Topol intercontinental ballistic missile from its northern test site in Plesetsk, as well as "several" shorter-range missiles from its submarines in the Northern and Pacific Fleets, news agencies cited defence officials as saying.

Other military manoeuvres involved the launch from an undisclosed location in western Russia of air-to-surface rockets by Tu-95 strategic bombers, and the entry into the English Channel of a Northern Fleet armada led by the aircraft carrier Admiral Kuznetsov.

The exercises, overseen by Putin and four visiting presidents from Kremlin-allied ex-Soviet states, were staged ahead of Russia's commemoration on Friday of the defeat of Nazi Germany in World War II.

Putin stressed in televised comments that the war games had been planned in November, implying that they were not directly linked to events in Ukraine.

But he told the visiting presidents from Belarus, Armenia, Tajikistan and Kyrgyzstan that Russia's nuclear defence capabilities remained strong and on constant alert.

"You have been able to witness the great readiness and cohesion of our country's offensive and defensive strategic forces," said Putin.