Saudi-led coalition jets targeting Houthi militiamen in Yemen killed 30 fighters loyal to Yemeni President Abd-Rabbu Mansour Hadi when they mistakenly bombed a military camp in the province of Taiz on Saturday, local officials said.
The airstrike, in which another 40 fighters were wounded, was the latest in a series of "friendly fire" incidents that have plagued the Saudi-led campaign against the Iranian-allied Houthis since it began in March.
Officials from the Saudi coalition and the Yemeni government could not immediately be reached for comment.
Saturday's strikes hit a mountainous area close to the southwestern city of Taiz, where fighting is intense between local fighters and troops loyal to veteran former President Ali Abdullah Saleh, who has sided with the Houthis, officials who are part of Hadi's administration told Reuters.
"The coalition raid hit the wrong target," one official said.
On Sept. 28, 131 people were killed when missiles fired from coalition planes hit a wedding party in the Red Sea village of al-Wahijah, near the ancient port of al-Mokha.
At least 5,400 people have been killed in the six-month civil war in the poorest country on the Arabian Peninsula, and the United Nations says the humanitarian situation, exacerbated by a Saudi blockade of Yemen's ports, is "critical."
Saudi Arabia has been leading an Arab military intervention since March to try to restore Hadi's government, now based in a hotel in Aden, and fend off what it sees as creeping Iranian influence.