U.N. Security Council members urged Yemen's Houthis to renew a truce that expired in October and to engage in substantive talks to end the more than eight-year-old conflict.

"I want the parties to the conflict to not only renew the truce but – crucially – to commit to taking steps towards a comprehensive resolution of the conflict," Hans Grundberg, the U.N. special envoy for Yemen, told a meeting of the council on Tuesday.

A two-month-long truce was originally agreed to on April 2 for the Muslim holy month of Ramadan. It led to a drop in civilian casualties and some relief in importing fuel and resuming commercial flights. The parties renewed it twice, but it expired on October 2 and the Iranian-backed Houthis have not agreed to extend it.

Despite its expiration, the U.N. envoy said the past seven weeks have not seen a resumption of full-fledged war. But recent Houthi attacks on oil terminals and seaports in the southern Hadramawt and Shabwa governorates have raised concerns of a return to the wider conflict.

"Attacks on oil infrastructure and threats to oil companies undermine the welfare of the entirety of the Yemeni people," Grundberg warned. "They risk setting off a spiral of military and economic escalation, a pattern we have seen play out before over the course of Yemen's war."

Last week in the Gulf of Oman, the U.S. Navy said it interdicted 170 tons of materials used as missile fuel and explosives hidden aboard a ship bound from Iran to Yemen.

-Agencies