UN Secretary-General Antonio Guterres on Thursday expressed alarm at the continued airstrikes in Sanaa, Hodeidah and elsewhere in Yemen in recent days, said his spokesman.

Guterres also noted with alarm that missile attacks and shelling continued in several areas in the country. All of these actions have resulted in civilian casualties and damage to civilian infrastructure, said Stephane Dujarric, the spokesman.

"The secretary-general reiterates his call on the parties to exercise maximum restraint and prevent any escalation amid heightened tensions in the region, as well as to respect their obligations under international humanitarian law," the spokesman told a daily press briefing.

Yemen has been mired in a civil war since the Houthi militia overran much of the country and seized all northern provinces, including the capital Sanaa, in 2014. Saudi Arabia has been leading an Arab military coalition that intervened since 2015 to support the Yemeni government.

UN Special Envoy for Yemen Hans Grundberg has just left Riyadh after concluding a visit to Saudi Arabia. He met Saudi Vice Defense Minister Prince Khalid bin Salman, Yemeni Foreign Minister Ahmad Awad bin Mubarak, and other Saudi and Yemeni interlocutors, said Dujarric.

During his meetings, Grundberg also denounced the recent wave of military escalation, including the heavy airstrikes on Sanaa, which have engulfed Yemen and spilled over the borders to the United Arab Emirates and Saudi Arabia. Grundberg exchanged views on possible options to achieve immediate de-escalation and pave the way for comprehensive political talks, said the spokesman.