Saudi-backed government forces and Iran-allied Houthis in Yemen accused each other of violating a three-day ceasefire on Saturday as the United Nations sought to quell persistent fighting by extending the truce.

The ceasefire, which was due to end at midnight local time on Saturday, was aimed at paving the way for talks to end a 19-month war in the Arab world's poorest country and allowing badly needed aid to be delivered.

Ground fighting has raged largely unabated despite the truce, but air attacks on the capital, Sanaa, have stopped and there were fewer Houthi missile strikes on Saudi Arabia, residents and local officials said.

A Saudi-led coalition backing the exiled government accused the Houthis of violating the ceasefire almost a thousand times in the last 24 hours by launching mortar and armed attacks along Yemen's border with the kingdom and in several Yemeni provinces.

Houthi-run Yemeni state news agency Saba said Houthi forces had repelled government advances backed up by Saudi-led air strikes toward the capital Sanaa from multiple directions.

Ali Mohsen al-Ahmar, the exiled vice president and a powerful military leader, said after a meeting with the U.N. special envoy to Yemen in Riyadh late on Friday that the government sought peace but would respond to Houthi attacks.

"The legitimate government remains committed to restraint in recognition of the efforts of U.N. and for the sake of achieving the peace which has been rejected by the coup militias," Ahmar said in a statement on his official Facebook page.

Ahmar said U.N. envoy Ismail Ould Cheikh Ahmed asked to extend the truce for another 72 hours, and government sources told Reuters foreign diplomats also were lobbying both sides to prolong the ceasefire.

The Houthis have also called for a negotiated solution to the conflict but were yet to agree on a truce extension.