At least 12 people were killed and 309 others wounded in a strike on Riyadh's international airport, Saudi Arabia's civil aviation officials said - an attack that a diplomatic source blamed on Yemen's Houthis.

While one official said the Riyadh airport has been evacuated, the other said air traffic has stopped, speaking on condition of anonymity.

The attack prompted Saudi health officials to activate a rare mass call-up of doctors to deal with the "serious emergency", a medical source said.

The attack prompted Saudi health officials to activate a rare mass call-up of doctors to deal with the "serious emergency", a medical source said.

Two regional officials say the airport in the Saudi capital has been attacked again.