Russian experts have confirmed from pictures of the wreckage that the projectile falling in Poland was a Ukrainian missile, the Russian Defense Ministry said on Wednesday.
The rocket was an anti-aircraft guided missile of the S-300 air defense system of the Ukrainian air forces, the ministry said in a statement.
Accusations by various sources about Russian missiles hitting the Polish village of Przewodow near the Polish-Ukrainian border were "a deliberate provocation with the aim of escalating the situation," it stressed.
The Polish government confirmed on Tuesday night that two Polish citizens had been killed in explosions in the Polish city of Hrubieszow near the Poland-Ukraine border, amid media reports over missiles falling there in the afternoon.
The cause of the explosions remains unclear. TVP and TVN, among several mainstream Polish media outlets, said early Wednesday that the blasts were reportedly caused by Russian rockets, but Poland's President Andrzej Duda said later that there was no indication that the blast was an intentional attack on Poland.
Addressing a press conference in Warsaw following a meeting of his country's National Security Bureau on Wednesday, Duda said: "We have no proof at this stage that it was a missile launched by Russia. There are many indications that it was an air defense missile that unfortunately fell on Polish territory."
Jens Stoltenberg, secretary general of the North Atlantic Treaty Organization (NATO), said in Brussels on Wednesday that the explosion was likely not an attack from Russia but was caused by a Ukrainian air defense missile.
Citing the findings of a preliminary analysis of the debris found at the site of the explosion, Stoltenberg said after a NATO emergency meeting in the Belgian capital on this issue that: "We have no indication that this was the result of a deliberate attack. And we have no indication that Russia is preparing offensive military actions against NATO."
An investigation by NATO into the incident is still ongoing, Stoltenberg and Duda both said.