Yemeni Houthi rebels have issued new warnings to international airlines about using airports in Saudi Arabia, urging serious attention to their alerts, according to statements on Monday.

Earlier, the Saudi Arabian General Authority of Civil Aviation reported that a Houthi attack on Riyadh's main airport resulted in 12 deaths and 309 injuries.

Former U.S. President Donald Trump said the United States is maintaining contacts with the Houthis, while U.S. Senator Marco Rubio accused the group of carrying out the attack.

Saudi Arabia has vowed to respond to the assault on Riyadh airport.