A leading rights group has called the recent drone attack by Yemen's Houthi rebels on an airport in Saudi Arabia an "apparent war crime."

Human Rights Watch urged the Houthis to stop attacks on civilian infrastructure in Saudi Arabia. Michael Page, deputy Middle East director at HRW, said "unlawful Saudi-led coalition airstrikes in Yemen never justify Houthi attacks on Saudi civilians," according to a statement Friday.

The Houthi attack on the southwestern Saudi town of Abha's regional airport wounded 26 people Wednesday.

A Saudi-led military coalition has been fighting the Houthis since March 2015. The conflict in the Arab world's poorest country has killed an estimated 60,000 people and left millions suffering from lack of food and medical care.