A Houthi official warned the United States on Monday that it would face a "swift, painful response" if it entered the war in Yemen.

The warning came amid reports that Saudi Arabia has requested Washington's assistance in dealing with the Houthi group, as the kingdom continues to weather repeated attacks.

Saudi Arabia has accused the Houthis of killing 12 people and injuring 300 others in an attack on King Khalid International Airport on Saturday.

The casualty figures were reported by sources covering the conflict, though full details of the airport strike were not available in the provided reports.

The Houthi movement, which controls large parts of northern Yemen including the capital Sanaa, has carried out a sustained campaign of drone and missile strikes against Saudi Arabia throughout the conflict.