Moscow has accused Ukraine of deadly air strikes on south-west Russia - with 18 people killed and more than 100 injured in Belgorod, near the border.
The regional governor said three children were among the dead in what was one of the deadliest attacks on Russia since it invaded Ukraine.
A Ukrainian security source insisted that only military infrastructure had been targeted in the action.
The attacks follow Russian strikes on Ukraine on yesterday which killed 39.
Those strikes were described by Kyiv as Russia's biggest missile bombardment of the war so far.
Moscow accused its neighbour of launching the attack with multiple forms of weaponry - including Ukrainian Olkha and Czech-made Vampire rockets.
The Ukrainian security source says more than 70 drones had been launched against Russian targets, as a "response to Russia's terrorist attacks on Ukrainian cities and civilians".
Source: BBC
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