Huthi fighters have intensified operations against the kingdom as air strikes by the Saudi-led military coalition pound rebel positions in the north of Yemen, in a bid to stop their offensive to seize the government's last northern stronghold of Marib.

Years of war have already pushed Yemen to the brink of famine.

Saudi Arabia -- which has been backing the Yemeni government against the rebels since 2015 -- said Saturday it thwarted a Huthi missile that targeted Riyadh.

"The operation was carried out with a ballistic missile and 15 drones... targeting sensitive areas in the enemy's capital of Riyadh," said Huthi spokesman Yahya al-Saree, according to the rebels' Al Masirah TV channel.

"Our operations will continue and will expand as long as the aggression and siege on our country continues."

Fragments of the missile scattered over several Riyadh neighbourhoods, damaging at least one home but no casualties were reported, Saudi state-run Al Ekhbariya television said.

AFP correspondents in the Saudi capital reported hearing multiple loud explosions, with state television footage showing the night sky light up with a bright flash.

Separately, the coalition said it had intercepted six Huthi drones targeting the kingdom, including the southern cities of Khamis Mushait and Jizan.

Saree on Sunday claimed those attacks as well, warning residents in the region to "stay clear from all military airports and sites".

- 'Catastrophe' -

The Huthis have escalated cross-border attacks on the kingdom even after the United States delisted the rebels as terrorists, reversing a decision by the administration of former president Donald Trump.

The designation had been widely criticised by aid organisations, who warned it would hamper their efforts to alleviate a humanitarian crisis in Yemen.

US President Joe Biden halted support to Saudi offensive operations in Yemen's war, which he called a "catastrophe" that "has to end".

But he has also reiterated US support for Saudi Arabia in defending its territory.

British Foreign Secretary Dominic Raab condemned the Huthi strikes.

"These put innocent lives at risk and show that those responsible are not serious about peace, let alone protecting the Yemeni people," he tweeted.

On Sunday, in the latest violence in Yemen, five civilians, including a child, were killed when their home was destroyed in a bombardment near the strategic rebel-held Red Sea port of Hodeida.

The warring sides traded blame over who was responsible, with the government accusing Huthis of firing a mortar bomb and the rebels saying the explosion was caused by twin air strikes by the Saudi-led coalition.

Alongside the cross-border attacks, the Huthis are pressing ahead with an offensive to seize the government-held Marib region, where some of the country's richest oil fields are found.

Hundreds of fighters from both sides have been killed in recent ferocious fighting, government sources say.

The Huthis control most of the country's north and the government has been struggling to defend Marib province and the city, which lies some 120 kilometres (75 miles) east of the rebel-held capital Sanaa.

Yemen's conflict has claimed tens of thousands of lives and displaced millions, according to international organisations, sparking what the UN calls the world's worst humanitarian crisis.

The UN on Monday hopes to raise $3.85 billion at a donor conference to support millions of civilians and prevent famine in the country.

In an interview with AFP Sunday, UN Development Programme country director, Auke Lootsma, urged the international community to "rally around Yemen and come forward with a great number of pledges that will help us to prevent a widespread famine".

He warned as well that with the infrastructure damage caused by the conflict, Yemen is now witnessing "the worst development crisis in the world" and risks becoming an "unviable state".