The prosecutor's office in Poznań, western Poland, said on Tuesday that the probe concerns a deliberate attack on civilians.
The attack occurred on November 19, when a residential building in Ternopil collapsed after being struck by a Russian missile, Polish state news agency PAP reported.
According to Ukrainian officials, the strike killed at least 34 people, including six children. Among the victims was a seven-year-old Polish girl.
"The District Prosecutor in Poznań has initiated an investigation into the killing of a minor and violations of international law," said Łukasz Wawrzyniak, spokesman for the Poznań prosecutor’s office.
Ukrainian authorities are conducting a parallel inquiry, and Polish prosecutors have requested assistance from the Ukrainian embassy to obtain case files.
Deliberate attacks on civilians carry a sentence of at least 12 years in prison, or life imprisonment, under Polish law.
(ał/gs)
Source: PAP