Deputy Defence Minister Cezary Tomczyk said the missile, which can carry a nuclear warhead, crashed in a field near the village of Tarnawa-Kolonia in Poland's eastern Lubelskie region after entering Polish airspace during Russia's latest missile barrage against Ukraine, Polskie Radio reports.
"I spoke with Operational Commander Gen. Ireneusz Nowak, and we can confirm with full responsibility that it was a Russian Kh-101 cruise missile, capable of carrying nuclear warheads, which exploded on impact with the ground," Tomczyk told broadcaster TVN24.
He described the missile as "potentially very dangerous" but said authorities still did not know whether it had entered Poland intentionally.
"All scenarios remain possible," Tomczyk said. "We simply do not know, and if we do find out, it will mainly come from intelligence information."
He told TVN24 that Russia typically launches 10 to 20 Kh-101 missiles in attacks on Ukraine but said about 70 missiles were fired overnight, with roughly 20 heading toward Poland around 3 a.m.
Earlier on Thursday, Prime Minister Donald Tusk said there was no indication Poland had been the intended target.
He said military experts believed the recovered fragments and other evidence strongly pointed to a Russian Kh-101 missile, but cautioned that investigators had not yet reached a final conclusion.
Tusk also said Polish forces had been prepared to shoot down the missile if it had posed a direct threat to populated areas.
The Operational Command said an unidentified object was detected in Polish airspace at 3:40 a.m. local time.
An F-16 fighter jet was scrambled to intercept it, but the object disappeared from radar screens before it could be positively identified.
An Mi-24 helicopter later located the probable impact site near Tarnawa-Kolonia.
The missile struck an uninhabited area, leaving a crater but causing no casualties or property damage.
The District Prosecutor's Office in the regional capital Lublin, which is leading the investigation, said earlier on Thursday that the object was most likely a Kh-101 missile carrying a significant quantity of explosives.