"The Russian side warned the Americans about the launch of 'Oreshnik'," through an automatic nuclear de-escalation hotline, Kremlin spokesman Dmitry Peskov told the TASS news agency, using Russia's name for the missile.

Putin said earlier that Russia had test-fired a new type of hypersonic intermediate-range missile at the Ukrainian city of Dnipro that was equipped with a non-nuclear warhead.

Kyiv had accused Russia of firing an intercontinental ballistic missile (ICBM), but said tests were being carried out on debris to ascertain which type of weapon and warhead were used.

Peskov said Russia's National Centre for the Reduction of Nuclear Danger sent a message to a similar service in the United States "automatically" 30 minutes before the planned launch, TASS reported.