Saudi Arabia threatens Qatar 'military action' following S-400 sale

Saudi Arabia has threatened to launch military action against neighbour Qatar, if it goes again with the purchase of Russia's S-400 anti-aircraft missile system, according to French media.

King Salman sent a letter to French President Emmanuel Macron warning that Saudi Arabia might use force to prevent Qatar from acquiring the S-400, Le Monde reported on Friday.

In the letter, Salman expressed his "profound concern" about the slated sale of the leading Russian anti-aircraft missile system to blockaded Qatar and asked the French president to intervene.

"[In such a situation], the kingdom would be ready to take all the necessary measures to eliminate this defence system, including military action," the Saudi king reportedly wrote in the letter.

Le Monde said the information was passed on by an aide to Macron.

Qatar has been blockaded by Saudi Arabia since June 2017, when Riyadh accused the Gulf state of "supporting terrorism" and being "too close" to Iran - claims Doha has strongly denied.

UAE, Bahrain and Egypt joined Riyadh in the blockade of Qatar, cutting diplomatic ties and halting land, sea and air routes to the Gulf peninsula state.

Qatar ambassador to Russia announced in January that Doha was in an "advanced stage" of acquiring the S-400.

The S-400 has been described as "one of the best air defence systems" in the world, and has attracted interest from a number of states in the region, including Turkey, Saudi Arabia and Iraq.

The slated sale of the S-400 to Turkey has also angered its western allies in NATO, wary of Ankara's growing military ties with Moscow.

The Saudi-led coalition has made a number of military threats against Qatar, including regime change, cutting off the peninsula state with a man-made canal, and invasion.

Qatar has US and Turkish military bases on is territory.