Saudi Arabia's air defence forces intercepted a ballistic missile over Riyadh, Al Arabiya reported on Wednesday, after at least three blasts were heard and three clouds of smoke were seen in the sky above the capital. Yemen's Houthis targeted Saudi Arabia's defence ministry in Riyadh, the armed group's Al Masirah TV said on Twitter. There were no immediate reports of damage. Yemen's Houthi militia has stepped up missile attacks on the kingdom in what it says is retaliation for air raids by a Saudi-led coalition fighting the Iran-aligned armed movement. One man was killed in Riyadh last month by debris after the military shot down a flurry of missiles, the first casualty of the Yemen war in the Saudi capital. Saudi Arabia and a coalition of mostly Gulf Arab states intervened in Yemen's civil war in 2015 to try and push back the Houthis after the movement drove the internationally recognised government into Saudi exile. The attack on Wednesday marked the fourth time in five months that missiles have flown over Riyadh, as the Houthis step up efforts to demonstrate they can reach the Saudi capital, and threatens to escalate a regional rivalry between Iran and Saudi Arabia. *This story was edited by Ahram Online.