Saudi forces suffered dozens of casualties amid clashes in the country's southwest, according to news reports on Sunday by an outlet aligned with Yemeni Houthi rebels.
Clashes broke out with Houthi forces in the city of Najran, the Ansarullah news website reported. Saudi authorities have yet to comment.
Middle East Monitor has been unable to verify the reports independently.
Yemen has been beset by violence and chaos since 2014, when Houthi rebels overran much of the country, including Sanaa. The crisis escalated when a Saudi-led military coalition launched a devastating air campaign aimed at rolling back Houthi territorial gains.
The coalition intervened in Yemen in March 2015 after the Houthis ousted the Saudi-backed, internationally recognised government from the capital, Sanaa, in late 2014.
Tens of thousands of Yemenis are since believed to have been killed in the conflict, while another 14 million are at risk of starvation, according to the UN.
The Houthis, who control most large urban centres, say they are fighting a corrupt system.