Yemen's government and rebels doubled down on their rival demands Thursday, just moments before hard-won peace talks were due to open in Sweden under the auspices of the United Nations.

A top Houthi rebel official threatened Thursday to bar UN planes from using the Sanaa airport unless peace talks in Sweden lead to its full reopening.

"If the Yemeni capital's airport is not opened to the Yemeni people in the peace talks in Sweden, I call on the (rebel) political council and government to close the airport for all planes," Mohammed Ali al-Houthi tweeted.

The Yemeni government hit back, demanding the rebels withdraw from the flashpoint port city of Hodeida.

Yemen's Foreign Ministry demanded the "coupist militias withdraw fully from the western coast and hand the area over to the legitimate government" via Twitter -- a reference to rebel-held Hodeida, home to Yemen's most valuable port.

The Sweden talks mark the first attempt in two years to broker an end to the Yemen conflict, which has killed at least 10,000 people since 2015 and triggered what the UN calls the world's worst humanitarian crisis.

Some 14 million people are at imminent risk of starvation in Yemen, according to UN estimates, as a Saudi-led military coalition continues to battle the country's Iran-backed Houthi rebels.