Saudi Arabia's permanent representative in Geneva says his country sent letters to the U.N. humanitarian agency chief calling on aid groups to "be careful" to avoid damage from air strikes led by the Saudi-led coalition in war-torn Yemen.

Ambassador Faisal Bin Hassan Trad cited one Saudi letter to OCHA chief Stephen O'Brien which said the coalition's request for caution "in no way can be misinterpreted to indicate any hindrance to humanitarian access and the delivery of the humanitarian assistance in Yemen."

Trad told reporters Friday: "We did not tell anyone to leave anyplace. We told them, 'Please be careful. Do not be near ... legitimate targets, military targets.'"

The U.N. estimates over 5,800 people have died in Yemen's conflict between Shiite rebels and the internationally-backed government.