Three Saudi soldiers have been killed in a clash with armed "hostile elements" who attempted to infiltrate the border from Yemen, the interior ministry said on Monday.
The clash erupted on Sunday evening hours after a Saudi border guard and two Yemeni civilians were killed in separate incidents in the border region, according to the ministry.
In the latest incident border guards in the southwestern Jazan district "confronted... an infiltration attempt by hostile elements" who targeted military posts with gunfire and rockets, the ministry said.
The infiltrators were "forced to retreat" but three soldiers were killed in the clash, it added in a statement carried by the official Saudi Press Agency.
The ministry did not specify if the infiltrators belonged to the Iran-backed Shiite Huthi rebels who frequently clash with Saudi forces and bomb the border region.
Close to 80 people have been killed in border shelling and skirmishes since Saudi Arabia and its allies launched a military intervention against the Huthis in its southern neighbour in March.
Most of the casualties have been soldiers.
In Yemen, the United Nations says more than 5,700 people have been killed since March, nearly half of them civilians.