RIYADH: Saudi Arabia's powerful crown prince accused Iran on Tuesday of "direct military aggression" through Yemen's Huthi rebels, ratcheting up regional tensions as the kingdom reels from a sweeping royal purge.

In the latest flare-up, Saudi Arabia on Saturday intercepted and destroyed a ballistic missile near Riyadh international airport, reportedly fired from Yemen by Iran-backed Huthi rebels, provoking a bitter war of words.

Saudi Arabia accused Iran of supplying missiles to the rebels. Tehran vehemently denied the charge and in turn accused Riyadh of war crimes in Yemen.

"The involvement of Iran in supplying missiles to the Huthis is a direct military aggression by the Iranian regime," the Saudi Press Agency quoted Crown Prince Mohammed bin Salman as saying during a telephone conversation with British Foreign Secretary Boris Johnson.

This "could be considered an act of war," he said.

It was the first reported Huthi missile to reach Riyadh, with smouldering debris landing inside the King Khalid International Airport, underscoring the growing fallout for Saudi Arabia from its involvement in neighbouring Yemen.