GENEVA/CAIRO: Three people have been killed in attacks on Saudi airports, the country's civil aviation authorities said on Wednesday, as fighting intensified in Yemen between the Iran-aligned Houthis and Saudi-backed government forces.

One person was killed and eight wounded in an attack on King Khalid International Airport in the Saudi capital Riyadh, and two were killed and 28 wounded in an attack on facilities at Abha airport, it said in a statement.

One of the attacks was on Wednesday and the other on Tuesday, the civil aviation authorities said, without saying which attack had occurred on which day.

A Saudi-led coalition fighting the Houthis vowed retaliation, saying the attacks "will not go unpunished". In a statement issued late on Wednesday, the coalition said it had attacked more than 80 Houthi military sites across the governorates of Saada, Hodeidah, Jawf and Marib.