UNITED NATIONS, July 24 (Xinhua) -- UN Secretary-General Antonio Guterres is "deeply alarmed" by the resumption of Houthi attacks on commercial vessels in the Red Sea and the renewed threats to maritime navigation, his spokesperson said Friday.

"The attack on commercial vessels, claimed by the Houthis, risks further heightening regional tensions and widening the current cycle of escalation with the potential to draw Yemen deeper into regional conflict," spokesman 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," the spokesman warned.

Guterres called for immediate de-escalation and urged the Houthis to refrain from any further attacks or other escalatory actions. International navigational rights and freedoms in and around Bab al-Mandab must be fully restored, said the spokesman. ■