Yemen's internationally recognised, Saudi-backed government has alleged that the Houthi movement, backed by Tehran, has modified Iranian air defence weapons into loitering cruise missiles with the assistance of Iran's Islamic Revolutionary Guard Corps (IRGC).

Brigadier General Majed al-Nazili, spokesperson for Yemeni government forces, said the modified weapons operate on a thermal-tracking system and pose a danger to all aircraft in the region.

"These missiles move around for a period of up to 25 minutes per missile and operate using a thermal-tracking system and attack any heat source without the ability to distinguish between military or civilian targets," al-Nazili said in a statement. "This constitutes a direct and serious threat to the safety of civil aviation and the lives of passengers."

Al-Nazili warned that aircraft belonging to the United Nations or humanitarian organisations travelling via air routes over Yemen and the surrounding region could potentially be at risk.

"Threatening the airspace over the southern Red Sea and turning it into a danger zone for civilian aircraft and passengers represents an escalation that goes beyond the scope of Yemeni airspace safety alone," he said.

He also linked the development to recent statements by Iranian officials, including Mohsen Rezaei, secretary of Iran's Supreme National Security Council, who warned that regional airports could lose flights if they joined US restrictions on Iranian aviation. Rezaei's office later clarified that Tehran was not planning military retaliation over the restrictions, though it said non-military countermeasures against specific airports remained possible.

Al-Nazili called on international authorities to take "urgent and decisive action," stating that using "Iranian weapons from Yemeni territory poses a direct threat to international air navigation routes and cannot be considered a purely domestic Yemeni issue."

On Thursday, Saudi Arabia said it intercepted six ballistic missiles aimed at Taif in western Saudi Arabia and the Yanbu port area on the Red Sea.

The Houthis said they attacked "a sensitive target" in the Saudi capital, Riyadh, and Saudi Aramco facilities in Yanbu. Houthi military spokesman Yahya Saree said the group used ballistic and cruise missiles as well as drones in the two operations.

The Houthis were in open conflict with Yemen's government and a Saudi-led coalition of Arab states from 2014 until a United Nations-brokered ceasefire was declared in 2022. Fighting has reignited in recent weeks, with the Houthis seizing the Red Sea coast of Yemen along with the strategically important city of Mocha and Mayyun Island in the Bab al-Mandeb strait at the southern entrance to the Red Sea.

In July, the armed group declared a naval blockade against Saudi Arabia in the Red Sea.

Since the closure of the Strait of Hormuz, the Red Sea has become a vital alternative export route for Saudi Arabia. The country's East-West Pipeline, which carries oil from its eastern oilfields to the western port of Yanbu, is only just restarting operations after damage caused by a drone attack this month.