Ukrainian President Volodymyr Zelensky has denied that his country carried out an alleged drone attack on the Kremlin, which Russia says was an attempt on President Vladimir Putin's life.

Zelensky, who is currently on a trip to Finland, told reporters in Helsinki late Wednesday night: "We are not attacking either Putin or Moscow; we are fighting on our own territory, defending our villages and towns. We don't even have enough weapons to do that... That's why we didn't attack Putin; we'll leave that to the (international) tribunal."

The President further stressed that Russia has had no victories at the front and that Putin can no longer motivate Russian society and send soldiers to war for no reason, reports Ukrayinska Pravda.

"So it is in his (Putin) interest to accuse Ukraine of committing some crimes. He needs to do something drastic: either 'assassination attempts', drones, or some 'geese that bombed them'. They will come up with something or other every day.

"But the solution is simple: no need to intimidate anyone, no need to use weapons; you need to leave our territory," he added.

On Wednesday evening, the Kremlin press service said that Ukrainian drones had "attempted to strike" at the residence of Putin.

The Kremlin called the so-called attack a "planned terrorist action" and an "assassination attempt on the Russian President".

In response, Serhii Nykyforov, spokesman for President Zelensky, said that Ukraine had no information about the attack on the Kremlin.

"What happened in Moscow was clearly a Russian escalation of the situation," he added.

Unverified footage circulating online showed smoke rising over the Kremlin, reports the BBC.

A second video shows a small explosion above the site's Senate building, while two men appear to clamber up the dome.

Earlier on Wednesday, Russian strikes on Ukraine's southern Kherson region killed 21 people.

According to Zelensky, the shelling had hit "a railway station and a crossing, a house, a hardware store, a grocery supermarket and a gas station".

The victims included supermarket customers and employees of an energy company who were performing repairs, officials said.