A suicide bomber rammed an explosives-packed car into a Yemeni army checkpoint Friday, killing nine soldiers, a military source said, blaming Al-Qaeda for the attack.
Elsewhere, Riyadh said four Saudi security personnel were killed in cross-border rocket fire and shelling, while Yemeni sources said nine rebels were killed in clashes with pro-government forces in Dhaleh province.
The suicide bombing took place near the city of Qoton in southeastern Yemen's vast desert province of Hadramawt, where Al-Qaeda in the Arabian Peninsula (AQAP) operates.
The source said the dead soldiers were members of the army's First Division, loyal to exiled President Abedrabbo Mansour Hadi.
Hadi was forced out of the country earlier this year after Shiite Huthi rebels seized the capital and large chunks of Yemen.
Separately, the source said AQAP militants flogged eight people in the Hadramawt provincial capital of Mukalla, a port city of more than 200,000 people that they control.
Charged with offences including adultery and drug and alcohol use, the eight received between 80 and 100 lashes each in a punishment carried out in a public square before hundreds of witnesses.
In March, a Saudi-led coalition launched an air campaign against the Huthis and allied forces loyal to former president Ali Abdullah Saleh in a bid to restore the authority of Hadi, who has taken refuge in Riyadh.
AQAP, which Washington views as the extremist network's most dangerous branch, has taken advantage of the chaos gripping Yemen to make territorial gains in the south, including the seizure of Mukalla in April.
The Saudi interior ministry, meanwhile, said cross-border rocket fire and shelling killed three soldiers and a member of a paramilitary force in the Asir and Jazan regions.
The bombardment came during a day of relative calm in Yemen itself.
Government-aligned forces have since last week been expanding their area of control after recapturing the southern port city of Aden.
Nine rebels were killed in a clash with pro-Hadi forces in Dhaleh province on Friday, military sources said.
The clash and the border barrage came on the final day of what was supposed to be a ceasefire to allow in aid for Yemen's stricken civilians.
The humanitarian pause, declared by the coalition, began Monday but collapsed the next day.
According to the United Nations, the war has killed 3,984 people inside Yemen, nearly half of them civilians.
On the Saudi side of the frontier, about 50 people have been killed in skirmishes and shelling. Most casualties were members of the armed forces, but civilians have also died.
