With 24 hours left before the scheduled close of UN-brokered talks on Yemen, mediators pushed Wednesday for a truce between warring parties as a crucial step to allow aid deliveries.
UN Secretary-General Antonio Guterres was due in Rimbo late Wednesday for Thursday's closing round of consultations.
Both government and rebel representatives traded accusations of unwillingness to negotiate, particularly on rebel-held Hodeida, the main route for 90 percent of food imports and nearly 80 percent of aid deliveries.
Multiple draft proposals have been submitted to the two delegations over the past week. None have found consensus as yet.
"I think there is some progress, even if it's with much difficulty. It's slow progress," rebel representative Abdelmalik al-Ajri told AFP. "We are faced with the intransigence of the other side.
"Things should become clearer today."
Askar Zaeel, a member of the government delegation, said his camp would hold firm to UN Security Council Resolution 2216 -- which calls for the Huthis to withdraw from all areas seized in a 2014 takeover, including Hodeida.
The Yemen conflict has killed nearly 10,000 people since the Saudi-led coalition joined the war in 2015, according to the World Health Organization, triggering what the UN calls the world's worst humanitarian crisis.
Both parties stand accused of failing to protect civilians. The Saudi-led alliance has been blacklisted by the UN for the killing and maiming of children.
Guterres' arrival comes hours after his office said it had evidence the Huthis were using Iran-made missiles.
The Gulf monarchies and United States accuse Iran of supporting Huthi rebels -- and see this as justification for the military campaign they have waged in Yemen since 2015.
Iran supports the rebels politically but denies supplying them with arms.