UN Secretary-General Antonio Guterres has condemned Saturday's attack by Yemen's Houthi group on King Khalid International Airport in the Saudi capital of Riyadh.

"I am deeply shocked by and strongly condemn Saturday's lethal attack by the Houthis on King Khalid International Airport in Riyadh, the Kingdom of Saudi Arabia, which reportedly killed 12 people and injured hundreds of civilians," said Guterres in a statement on Sunday.

Attacks on civilians and civilian infrastructure violate international law, said Guterres, adding, "These attacks must cease immediately."