Poland's foreign ministry said Monday that the Russian ambassador in Warsaw failed to show for a summons issued after a Russian cruise missile breached Polish airspace over the weekend.
Poland said Sunday that a Russian cruise missile fired at towns in western Ukraine breached Polish airspace overnight and stayed for 39 seconds.
The army said the missile, which was travelling at almost 800 kilometres per hour (500 mph) around 400 metres (1,300 feet) above the ground, had crossed about two kilometres over the border into Poland.
Defence Minister Wladyslaw Kosiniak-Kamysz said Poland activated all air defence systems and the missile would have been shot down "had there been any indication it was heading for a target on Polish territory".
The "ambassador... did not appear at the foreign ministry today in order to explain the incident with the Russian cruise missile," ministry spokesman Pawel Wronski told reporters on Monday.
"We are wondering whether the ambassador is carrying out the instructions of the foreign ministry in Moscow and if he is able to properly represent Russia's interests in Warsaw," he said.
"A diplomatic note from the Polish foreign ministry demanding an explanation of the breach of Polish airspace will be transmitted another way to the Russian foreign ministry," he concluded.
A similar incident occurred on December 29, 2023, when a Russian missile penetrated Polish airspace for several minutes before returning to Ukraine.
In November 2022, two people were killed when a Ukrainian air-defence missile fell on the Polish village of Przewodow, close to the Ukrainian border.
Before the missile was identified as Ukrainian, fears were raised that NATO -- of which Poland is a member -- would be dragged into an escalation of the conflict with Russia if its collective defence provisions were triggered.