SANAA - The United Nations Special Envoy to Yemen Martin Griffiths arrived in the rebel-held capital Sanaa on Sunday to facilitate a humanitarian "medical air bridge", the Houthi rebel-run al-Masirah TV reported.

The air bridge, launched by the Saudi-led coalition in cooperation with the World Health Organization, is scheduled to open on Monday. Patients, with chronic diseases which cannot be treated inside Yemen, will be airlifted by UN chartered air flights from Sanaa airport to hospitals in Jordan and Egypt.

Yemen's airspace has been controlled by the Saudi-led coalition since its intervention in the Yemeni conflict in March 2015 to support the internationally-recognized government of President Abd-Rabbu Mansour Hadi.

Yemen has been mired in a civil war since late 2014, when the Iran-backed Houthis seized control of much of the country's north and forced the Saudi-backed government of Hadi out of Sanaa.