A Saudi-led coalition airstrike in Yemen hit allied forces in a friendly fire incident, killing at least 20, Yemeni security officials and pro-government fighters said on Sunday.
The officials said the strike late on Saturday hit the fighters on a coastal road as they headed toward the embattled city of Zinjibar in southern Yemen.
The Saudi-led, American-supported coalition began launching airstrikes in March against Shiite Houthi rebels and their allies, who control the capital and much of the country's north.
The fighting in Yemen pits the Houthis and troops loyal to former President Ali Abdullah Saleh against southern separatists, local and tribal militias, Sunni Islamic militants and loyalists of exiled President Abed Rabbo Mansour Hadi.
The United Arab Emirates said Saturday three of its soldiers were killed while taking part in a Saudi-led campaign. A statement carried by the official news agency WAM did not say how the soldiers were killed or whether they died in Yemen.
Five Emirati soldiers have been killed in battle since March.
Yemeni security officials have said that Saudi, Emirati, Egyptian and Jordanian military advisers are training hundreds of fighters at a military base near the port city of Aden.
All officials spoke on condition of anonymity because they were not authorized to speak to journalists.
Also Sunday, International Committee of the Red Cross President Peter Maurer said the organization has committed to doubling its program in the country to respond to the "catastrophic" situation.
"What the ICRC is doing and what the few other organisations are doing is by far not sufficient to cope with the dimensions of the humanitarian problem," Maurer said.
His comments came during a three-day visit to Yemen.