What is the S-300 missile that is reported to have hit Poland?

Poland has said the missile that hit a grain facility on Tuesday, killing two people near the border with Ukraine, was probably an "old" S-300 rocket, a Soviet-era missile system being used by both Russia and Ukraine.

NATO chief Jens Stoltenberg said it was likely being used as a Ukrainian air defence missile, but that Russia carried ultimate responsibility for the incident for having invaded Ukraine, triggering a now almost nine-month-old war. Russia at the time was firing scores of missiles at cities across Ukraine.

WHAT IS THE S-300?

The S-300 is a family of surface-to-air missiles, originally developed by the Soviet Union. It was first put into operation in the late 1970s after a decade of development.

There are several versions of the S-300 rocket, with different technical capabilities and ranges. The maximum range of the standard missile is 150 km (93 miles) and the warheads weigh 133-143 kg (293-315 lb), according to the Center for Strategic and International Studies (CSIS).

It is unclear which version might have been used in Tuesday's incident.