"The Secretary-General is deeply alarmed about the resumption of Houthi attacks on commercial vessels transiting the Red Sea and the renewed threats to maritime navigation," UN spokesperson Stephane Dujarric said in a statement.

"Further hostilities in Yemen will undermine prospects for peace, and cause serious economic, humanitarian and environmental consequences across and beyond the region," it added.

Guterres called for "immediate de-escalation" and urged the Houthis "to refrain from any further attacks or other escalatory actions," in line with UN Security Council Resolution 2722 (2024) and subsequent resolutions concerning attacks on commercial vessels and freedom of navigation in the Red Sea.