The Iran-backed Houthi militia in Yemen claimed responsibility on Monday for renewed attacks on neighbouring Saudi Arabia, as fighting intensifies along Yemen's Red Sea coast.

Houthi military spokesman Yahya Saree said the militia had attacked the Khamis Mushait airbase in southern Saudi Arabia with dozens of missiles and drones, targeting weapons depots, runways, hangars and other facilities.

He claimed the attack caused "significant losses," but gave no further details.

Saree said it came in response to more than 300 Saudi airstrikes on Yemen over the past few days.

Saudi Arabia, which has backed Yemen's internationally recognized government in its decade-long conflict with the Houthis, did not immediately comment on the Houthi claim.

The Houthis seized Sanaa and large parts of northern Yemen in 2014 and still control extensive areas of the country. In a recent offensive, they pushed south along the Red Sea coast toward the strategic Bab al-Mandab Strait.

According to Houthi circles and Yemeni government sources, the militia has also seized the strategically located islands of Mayun - also known as Perim - and Hanish.

The latest developments follow the Houthis' capture of the Red Sea port city of Mokha. It remains unclear whether, or for how long, the Houthis will be able to hold the newly captured territory.

A spokesman for the government-aligned Giants Brigades, Aseel al-Saqaladi, said the areas had since come under heavy bombardment. He described the Houthi offensive as a "catastrophe" for the militia and said it could mark the beginning of its defeat in Yemen.

"There is now an opportunity to wear them down," al-Saqaladi said.

The renewed offensive has sharply escalated Yemen's civil war and brought the Houthis closer to the Bab al-Mandab Strait, one of the world's most important maritime routes. The Houthis' advance to the Hanish Islands and Mayun has strengthened their position around the strait.

The developments could increase the threat to commercial shipping in the Red Sea. The Houthis have previously attacked vessels in the region, and their latest advances have raised concerns over their ability to exert greater pressure on shipping passing through Bab al-Mandab.

The Houthis have said they intend to ensure the safety of shipping in the area, while declaring Saudi vessels subject to a "blockade."