A six-month-old UN-brokered ceasefire in Yemen's war between Iran-backed Houthi rebels and a Saudi-led coalition ended on Sunday with no word from the rivals on whether it would be extended.
The conflict that started in 2014 has left hundreds of thousands dead and created what the United Nations has called the world's worst humanitarian crisis with widespread malnutrition and disease.
The ceasefire has twice been renewed since April 2 but neither the UN office in the rebel-held capital, Sanaa, nor the warring parties revealed whether talks were still going on.
The rivals have faced international calls to extend the measure, including from UN Secretary General Antonio Guterres, and even the United States and Russia came together at the UN Security Council to back the ceasefire.
UN envoy Hans Grundberg has shuttled between Sanaa and Oman, which has acted as a mediator, in a bid to secure an extension.
On Sunday, he met in Riyadh with the head of Yemen's presidential council, Rashad al-Alimi, the Yemeni news agency SabaNet reported.
Rebel leader Mehdi Mashat told a political meeting in Sanaa that the UN proposals did "not meet the aspirations of the Yemeni people", the rebels' Al-Massira TV reported.
Sporadic clashes were reported on Sunday in southwest Yemen, as coalition military sources said the Houthis had sent reinforcements to the region.
The Houthis said in a statement on Saturday that the ceasefire was at "a dead end".
"Over the past six months, we haven't seen any serious willingness to address humanitarian issues as a top priority," the statement said, accusing the coalition of failing to agree measures to "alleviate the suffering of the Yemeni people".
The lull has led to a 60 percent reduction in casualties while fuel imports into the Houthi-held port of Hodeida have quadrupled, humanitarian groups said on Thursday.
Sanaa residents say their daily lives have dramatically improved. Prices have come down as more essential goods entered the city even though key roads remain shut.
About 23.4 million of Yemen's 30-million population rely on humanitarian aid.
While the truce has largely held, the Houthis and the coalition blame each other for reported violations.
A siege remains in place on Taez, Yemen's third city, which is controlled by the government but surrounded by Houthi forces. (AFP)