RIYADH/ADEN, Yemen: Five Saudi Arabian border guards were killed Monday in clashes with “enemy elements” who tried to infiltrate the kingdom’s border with war-wracked Yemen, the Interior Ministry said.

The five were killed in eight hours of fighting when the Saudis confronted “enemy elements of armed groups who tried to infiltrate in several places” in the Najran area, the official SPA news agency quoted a ministry spokesman as saying.

It said the frontier guards backed by the country’s army thwarted the attempts to cross the border which began at 03:00 GMT.

Southern Saudi Arabia, especially border areas with Yemen, have come under sporadic attack since Riyadh took the lead in March 2015 in an Arab military coalition battling Houthi rebels who control northern Yemen.

Elsewhere, at least 80 pro-government and rebel troops have been killed in fighting since last week in northwest Yemen near the border with Saudi Arabia, military sources said Monday.

The clashes began Thursday when government forces launched an offensive aimed at retaking the towns of Haradh and Midi in Al-Hajjah province on the border.

“At least 48 [Houthi] rebels and forces loyal to [ex-President] Ali Abdullah Saleh were killed” in the fighting, one of the sources said.

Thirty-four loyalist soldiers were also killed, a pro-government source said.

Most of the soldiers were killed in explosions of land mines planted by the rebels, he said, adding that dozens were wounded on both sides.

Loyalist forces had succeeded in retaking a border post at the entrance of Haradh and pushing toward the town center, another military source said.

The offensive aims to advance on rebel-held Sanaa from the west after loyalist forces have so far failed to enter the capital from the east.

It comes as the Yemeni rivals hold U.N.-brokered peace talks in Kuwait that have so far failed to end the conflict that has killed more than 6,400 people since March last year.