Poland's air defence system initially detected the object but subsequently lost track of it.

Poland’s armed forces chief believes a Russian missile entered Poland for almost three minutes and then turned back into Ukrainian airspace.

Gen Wieslaw Kukula said the missile travelled about 40km (25 miles) into Polish airspace early on Friday. The alert coincided with what Ukraine has called Russia’s biggest day of air strikes since its war began. President Andrzej Duda convened an emergency security meeting after the object was picked up on radar. About 200 police officers have been conducting a search of the area where the object was detected in case the missile landed on Polish territory.