Saudi Arabia has given a $200 million cash infusion to Yemen's Central Bank to shore up its reserves after the war-torn country's currency went into freefall over the past few weeks.

The state-run Saudi Press Agency says the "donation" will help "achieve stability of the Yemeni economy and boost the local currency."

Saudi Arabia and key allies have denounced as "biased" a resolution that renewed a UN-backed investigation of alleged war crimes in Yemen, where Riyadh leads a coalition battling Shiite rebels.

A popular Yemeni writer with a large Twitter following has been held incommunicado by Saudi authorities for months, human rights groups said Wednesday, calling for his immediate release.

Marwan al-Muraisy, a social media activist with more than 100,000 Twitter followers, was arrested at his home in Riyadh on June 1, Reporters Without Borders (RSF) and other watchdogs said in a joint statement.

Saudi King Salman hosted Pakistani Prime Minister Imran Khan Wednesday on his maiden foreign visit since coming to power, state media said, as Islamabad seeks to stave off a financial crisis.

Saudi Arabia's diplomatic brawl with Canada has exposed what Western officials call "new red lines" in their engagement with the oil-rich kingdom, deterring nations from publicly criticising its human rights record.

Spain will go ahead with the controversial delivery of 400 laser-guided bombs to Saudi Arabia, engaged in a bloody conflict in Yemen, Foreign Minister Josep Borrell said Thursday.

The Saudi-led coalition backing the Yemeni government acknowledged Thursday there may have been "collateral damage" from August 23 strikes that the UN says killed 26 children south of the port of Hodeida.

Saudi Arabia shot down a ballistic missile fired by Yemen's Huthi rebels on Wednesday, with shrapnel leaving 26 people wounded, a Riyadh-led coalition fighting the insurgents said.

Spain said Tuesday it has cancelled a 2015 deal to sell 400 laser-guided bombs to Saudi Arabia, which is leading a coalition fighting rebels in Yemen.

More than 1,000 Saudi medical students ordered to leave Canada because of a diplomatic row have been granted an extension that would allow them to complete their training, Ottawa has confirmed.