The Saudi-led military coalition said Tuesday it had intercepted and destroyed drones and ballistic missiles launched into the kingdom by Yemen's Huthi rebels, including one fired towards Riyadh.

Witnesses told AFP that they heard blasts at dawn from their homes in the capital.

Coalition forces "managed... to intercept and destroy a ballistic missile launched by the terrorist Huthi militia from Sanaa towards Riyadh in a deliberate hostile operation," coalition spokesman Turki al-Maliki said on Saudi state media.

The alliance said it had intercepted "eight booby-trapped unmanned aircraft to target civilian objects and civilians in the kingdom", as well as three ballistic missiles.

The Iran-backed Huthis said on their Al-Masirah television that they had carried out a "major attack on Saudi soil", targeting military sites in Riyadh and the southern provinces of Najran and Jizan.

"We will carry out more and more powerful military operations," said Yahya Sarie, the spokesman for the Huthis' armed wing. 

Britain and the Organisation of Islamic Cooperation (OIC) both condemned the strikes, which took place months after the rebels seized the province of Al-Jawf, along the Saudi border, earlier this year.

Five years since the Saudi-led coalition intervened against the Huthis in Yemen, the Arab world's poorest country is devastated by conflict and malnutrition.

It now also faces a pandemic its decrepit health system is ill-equipped to handle.

British Foreign Secretary Dominic Raab said Tuesday that over a million Yemenis were believed to have contracted the novel coronavirus.

"It is more vital than ever that the Huthis cease their hostilities and allow the UN-led humanitarian response to get on with saving Yemeni lives," he said in a statement.

The Jeddah-based OIC said the strikes in Saudi Arabia targeted civilians and that it held the Huthis and "those who fund and arm them fully responsible for these terrorist acts".

Saudi Arabia was targeted with dozens of ballistic missile and drone attacks last year, including a devastating strike on oil giant Aramco's facilities which temporarily knocked out half the kingdom's crude output -- over five million barrels per day.

The attack was claimed by the Huthis, but the United States said it involved cruise missiles from Iran.

Yemen has been locked in conflict since the Huthis took control of the capital Sanaa in 2014 and went on to seize much of the north. 

The crisis escalated when a Saudi-led military coalition intervened to support the internationally recognised government. 

Tens of thousands of people, mostly civilians, have been killed and millions displaced in what the United Nations has called the world's worst humanitarian disaster.