WARSAW: Poland has no conclusive evidence showing who fired the missile that caused an explosion in a village near the Ukrainian border, the president said on Wednesday, adding that Warsaw remained calm in the face of what he described as a "one-off" incident.

Two people were killed in the explosion in Przewodow, about 6 km from the border with Ukraine, firefighters said. Media reports said the strike hit a grain-drying facility.

"We do not have any conclusive evidence at the moment as to who launched this missile ... it was most likely a Russian-made missile, but this is all still under investigation at the moment," Andrzej Duda told reporters.

The Polish foreign ministry had earlier said that a Russian-made rocket had fallen on the village.

Duda said that it was very likely that Poland would request consultations under Article 4 of the NATO military alliance following the blast.

"Our ambassador will be attending the meeting of the North Atlantic Council tomorrow at 10 a.m. at NATO headquarters ... it is highly likely that the ambassador will request the activation of Article 4, or allied consultations," he said.

Duda spoke after Prime Minister Mateusz Morawiecki said that Poland would increase surveillance of its airspace following the incident.

"We decided to increase the combat readiness of selected units of the Polish armed forces, with particular emphasis on airspace monitoring," Morawiecki said.

(SOURCE: Reuters)