Russia launched an intercontinental ballistic missile during an attack on Ukraine on Thursday, Kyiv's air force said, in the first known use in the war of a powerful weapon designed to deliver nuclear strikes thousands of kilometres away.

Security experts said that, if confirmed, it would be the first military use of an intercontinental ballistic missile (ICBM) - strategic weapons designed to deliver nuclear warheads and are an important part of Russia's nuclear deterrent.

The Ukrainians did not specify what kind of warhead the missile had or what type of missile it was. There was no suggestion it was nuclear-armed.

Russia did not immediately comment on the Ukrainian air force statement. Asked by reporters about the air force statement, Kremlin spokesman Dmitry Peskov told reporters to contact the Russian military for comment.