UNITED NATIONS, Dec. 26 (Xinhua) -- UN Secretary-General Antonio Guterres has condemned the escalation between Yemen's Houthis and Israel, and called for a ceasefire, his spokesperson said on Thursday.

"Israeli airstrikes on Sanaa International Airport, the Red Sea ports and power stations in Yemen are especially alarming," the spokesperson said in a statement.

The airstrikes reportedly resulted in numerous casualties, including an injury to a UN Humanitarian Air Service crew member.

According to the statement, a high-level UN delegation, headed by World Health Organization Director-General Tedros Adhanom Ghebreyesus, was at the airport when the strikes occurred.

The delegation had just concluded discussions on the humanitarian situation in Yemen and the release of detained UN and other personnel.

Expressing deep concern about the risk of further escalation in the region, the UN chief reiterated his call for all parties concerned to cease all military actions and exercise utmost restraint.

He also warned that airstrikes on Red Sea ports and Sanaa airport pose grave risks to humanitarian operations, the statement said. ■