President Volodymyr Zelensky has said he had "no doubts" that Ukraine was not to blame for the missile strike that killed two people in Poland on Tuesday.
Mr Volodymyr Zelensky said he had received assurances from his top commanders that "it wasn't our missile".
He also called for Ukrainian officials to be allowed to access the blast site and to be part of the investigation.
His comments came as Nato chief Jens Stoltenberg said Kyiv's air defence missiles were "most likely" to blame.
US President Joe Biden also cast doubt on Mr Zelensky's statement that the missile was not of Ukrainian origin, telling reporters "that's not the evidence".
Ukrainian air defence systems were activated on Tuesday when Russia launched what is believed to be its biggest wave of missile strikes since its February invasion.
The missile blast occurred on a farm in Przewodow, just 6km (4 miles) from Poland's border with Ukraine. The attack, which occurred during the G20 summit in Indonesia, caused an international outcry.
while news of a missile blast inside Nato member Poland's territory raised fears of a dangerous escalation in the war.
But Polish President Andrzej Duda said it was "highly probable" that the missile was launched by Ukrainian anti-aircraft defence.
Last week, Ukraine recaptured Kherson, the only major city to fall to Russia since it started its invasion in February.
And in the east, a Ukrainian offensive launched in September has seen Kyiv's forces advance into Donestsk and Luhansk.
Speaking to attendees of the G20 summit in Bali earlier this week, President Zelensky laid out a 10-point peace plan that includes nuclear safety guarantees,
the withdrawal of Russian troops from Ukraine's territory, and reparations and justice for "Russia's aggression against Ukraine".