The UN's Yemen envoy returned to the capital Sanaa on Wednesday for fresh talks with rebels, as the government threatens to resume its offensive on a key port city if mediation fails.
Pro-government forces backed up by a coalition led by Saudi Arabia have paused their assault on Hodeida port in a bid they say to give UN-led peace efforts a chance.
UN envoy Martin Griffiths has been pushing for weeks to relaunch negotiations between Yemen's internationally recognised government and Iran-backed Houthi rebels.
The government is looking for the Houthis to withdraw from Hodeida before peace talks can resume and insists Yemeni authorities must take control of the city.
A senior official said the government would accept the presence of international observers to "oversee the management of the port and the delivery of financial revenues" to the central bank it controls.
If mediation fails, pro-government forces warn they could restart the offensive on the vital lifeline port, which has sparked fears that it could worsen the dire humanitarian crisis in Yemen.
"Our forces are ready and waiting for the green light to resume the attack on the city of Hodeida if the international envoy's mission fails," a Yemeni military official told AFP.
Rebel leader Abdulmalik al-Houthi said in an interview last week with Le Figaro that he was ready to hand over control of Hodeida's port to the UN if pro-government forces stopped the offensive.
Griffiths arrived at Sanaa's airport at noon and headed immediately to his residence without making a statement to the press, an AFP photographer said.
The envoy's visit to Sanaa comes after meetings in Riyadh on Sunday with Yemeni government officials, who demanded the rebels release all detainees.
Hodeida's port is the entry point for some 70 percent of imports in a country where eight million people face imminent famine.
The Red Sea port has been controlled by the rebels since 2014, when they drove the government out of the capital Sanaa and much of the country.
The government and the Saudi-led alliance accuse the Iran-backed rebels of receiving smuggled weapons through Hodeida and have demanded their unconditional withdrawal from the city.
Saudi Arabia, the UAE and other allies intervened in the conflict between Yemen's government and rebels in March 2015, aiming to push back the Houthis and restore the internationally recognised government to power.
Nearly 10,000 people have been killed in the Yemen conflict since the 2015 intervention, 2,200 of them children.