A friendly-fire airstrike from the Saudi-led coalition in Yemen killed at least 30 pro-government soldiers and wounded 40 others on Saturday.
The incident happened while coalition forces in pursuit of Shiite Houthi rebels in southern Yemen struck a pro-government military encampment, military officials said.
The fighters had just forced out the Houthis from the encampment in Taiz province when the airstrikes hit them.
"They thought the Houthis were still there," one pro-government security official said.
Around 40 were wounded by the strike on Waziya, an area between Taez and Lahj provinces.
The Saudi-led coalition, backed with logistical and intelligence support form Britain and the US, has been heavily criticized for its bombing campaign in Yemen by a number of international organizations and humanitarian groups.
The Arab coalition commanders on the ground have repeatedly complained about slow communication with military leaders in Riyadh.
The UN called on Riyadh to halt its campaign after releasing estimates that indicated more than 2,300 civilians had been killed and a further 4,800 wounded in the country since the airstrikes started in March.
A recent report released by the UN high commissioner's office found that close to two-thirds of reported civilian deaths "had allegedly been caused by [Saudi-led] coalition airstrikes, which were also responsible for almost two-thirds of damaged or destroyed civilian public buildings."
Clear evidence of #warcrime, Saudi jets while throwing cluster bombs on village in #Yemen @JamilaHanan @A7medJa7af pic.twitter.com/YBBjTGGRj8
— Badi' al-Zaman (@I4Yemen) October 17, 2015
Many victims have not been rebel fighters, but rther Yemeni civilians, and reports indicate children as young as 12-months-old have been among those killed by airstrikes.
Saudi Arabia's stated aim is to oust the Houthi rebel group, which took control of large swathes of the country earlier this year, and to return the government of Abd Rabbu Mansour Hadi to power.
