Russia will supply Qatar with an anti-aircraft missile system despite reported Saudi threats to take military action over the deal, the state-run Sputnik news agency reported.
A Russian lawmaker made the remarks on Saturday, after French daily Le Monde reported that the Saudi King had warned he might use force to prevent Qatar from acquiring the S-400 system.
"Russia seeks its own interest, supplying S-400 to Qatar and earning money for the state budget. Saudi Arabia's position has nothing to do with it, Russia's plans will not change," Aleksei Kondratyev said.
"It is clear that Riyadh plays a dominant role in the region, but Qatar gets an advantage by enhancing its Armed Forces due to the acquisition of Russian S-400 systems. Therefore, Saudi Arabia's tension is understandable," he added.
King Salman reportedly sent a letter to French President Emmanuel Macron warning that Riyadh could use force to prevent Qatar from acquiring the anti-aircraft missile system.
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.
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.
In April, Saudi Foreign Minister Adel al-Jubeir warned Doha that it faced "imminent demise" unless it funded a US military presence in Syria.