U.N. chief Antonio Guterres on Saturday condemned an exchange of attacks between Yemen's Houthi rebels and the Saudi-led coalition, calling for "restraint" on all sides in the seven-year conflict.
"The Secretary-General strongly condemns the recent escalation of the conflict in Yemen," U.N. spokesperson Stephane Dujarric said in a statement Saturday.
The wave of rebel assaults included an attack at an oil plant that set off a huge fire near Jeddah's Formula One circuit during televised practice sessions on Friday.
In response, the Saudi-led coalition launched air strikes on the capital Sanaa and the port city of Hodeida -- a key entry point for humanitarian aid -- early Saturday. The strikes on Sanaa reportedly killed eight civilians, the U.N. statement said.
The exchange of fire came ahead of the seventh anniversary of a Saudi-led coalition's military intervention to support Yemen's government against the Iran-backed Houthis, after they seized Sanaa in 2014.
Earlier Saturday, Houthi rebels announced a three-day truce with the Saudi-led coalition and dangled the prospect of a "permanent" cease-fire. There was no immediate response from Saudi Arabia.
Dujarric said the U.N. chief reiterated "his calls upon all parties to exercise maximum restraint" and to "urgently reach a negotiated settlement to end the conflict."
The statement also called out the coalition strikes, which destroyed explosive-laden boats in Yemen, for damaging a U.N. staff residential compound in Sanaa.
Thousands of people marched in the Yemeni capital on Saturday to denounce the conflict, which has killed hundreds of thousands directly or indirectly, according to the U.N., and left millions on the brink of famine.