A Saudi-led coalition resumed airstrikes Sunday near Yemen's capital, Sana'a. The strikes came just hours after a 72-hour cease-fire expired.
U.N. special envoy Ismail Ould Cheikh Ahmed said he had hoped the cease-fire would continue. "We would like to build on this and we aim for a wider outreach in the next few days," he said.
Both sides seemed to adhere to the cease-fire, Ahmed said, "despite reported violations from both sides in several areas."
Fighting in Yemen, with government forces and their Saudi-led allies battling Houthi rebels backed by Iran, raged from Friday into Saturday on the Saudi-Yemen border, despite the cease-fire that ended late Saturday.
Witnesses reported Saudi-led coalition airstrikes Saturday on Houthi missile launchers east of Sana'a.
All parties had agreed to honor the U.N.-backed truce as a means to allow critically needed supplies to reach civilians cut off from outside help.
Ahmed described the truce as an opportunity to establish a foundation for talks to end nearly two years of civil war in Yemen, which borders Saudi Arabia. Monitors say nearly 7,000 people — at least half of them civilians — have died since the uprising began.
On Friday, Ahmed described the truce as "fragile, but largely holding."
Late in the day he met in the Saudi capital with exiled Yemen Vice President Ali Mohsen al-Ahmar, and said afterwards that Yemeni government forces were "exercising restraint" in the face of what he said were more than 400 truce violations by Shi'ite rebel fighters.
The cease-fire was the sixth formal attempt to end the fighting since the Saudi-led Sunni coalition of Gulf states intervened early last year to support the internationally recognized Sunni government of President Abdu Rabu Mansour Hadi.
Houthis launched their rebellion in 2014 after years of accusing the Sunni-led Sana'a government of widespread discrimination.