Dazzling installations have been lighting up the Saudi capital, bringing a taste of the kingdom's push to become a global arts destination to ordinary Saudis -- not just habitual museum-goers.

A massive red orb glowing outside the national library, illuminated rods dotting the riverside at a popular picnic spot, and Arabesque designs projected onto the mud-brick walls of a 130-year-old fort -- these are all part of Noor Riyadh, a city-wide festival.

US President Joe Biden Wednesday said that Elon Musk's ties with foreign countries were "worthy" of scrutiny, amid questions over the Saudi acquisition of a stake in Twitter as part of the tycoon's blockbuster takeover.

"I think that Elon Musk's cooperation and/or technical relationships with other countries is worthy of being looked at," Biden said, answering a question from a reporter after a long pause.

"Whether or not he is doing anything inappropriate, I'm not suggesting that... That's all I'll say," he said.

The family of Egypt's jailed dissident Alaa Abdel Fattah, who is refusing food and water, demanded information on his health Wednesday amid what they said were "rumours of force-feeding".

International concern has mounted since Abdel Fattah, 40, escalated his months-long hunger strike by also declining liquids since Sunday, the start of the UN climate summit COP27 hosted by Egypt.

His UK-born mother Laila Soueif has made daily trips this week to the Wadi al-Natroun prison, about 100 kilometres (60 miles) north of Cairo, but has received no update or proof of life.

The United States launched Wednesday a partnership with private funds aimed at supporting the transition to renewable energy in developing nations, based on a carbon credit system criticised by climate activists.

The government scheme, launched at the COP27 climate conference in Egypt along with the Bezos Earth Fund and Rockefeller Foundation, would help emerging economies attract finance "to support their clean energy transitions", Washington said.

The International Criminal Court's chief prosecutor said Wednesday he had urged eastern Libyan military chief Khalifa Haftar to "prevent" crimes by his troops, as investigations into their actions continue.

Karim Khan, the first ICC prosecutor to visit the war-torn country in a decade, arrived in Libya on Saturday.

The North African nation descended into chaos following the NATO-backed revolt that brought down dictator Moamer Kadhafi's regime in 2011 -- with rival administrations based in east and west and a myriad of militias scattered across the country.

Planet-heating emissions from oil and gas production could be three times higher than reported, according to a satellite monitoring project launched Wednesday that the UN chief said made it harder to "cheat".

The new tool -- unveiled at United Nations COP27 climate talks in Egypt -- has pinpointed more than 70,000 sites spewing emissions into the atmosphere.

The project, run by a group of research institutions, charities and companies, monitors sites including heavy industry, energy production, agriculture, transport, waste and mining.

A trickle of climate "loss and damage" funding pledges from rich countries at the COP27 summit in Egypt have been welcomed by observers and developing nations, who say they must pave the way for a broad global financing deal.

The controversial issue is a key focus of the UN meeting, as a relentless surge of impacts wreak death, destruction and mounting economic losses on developing nations least responsible for planet-heating emissions.

Investment in renewable energy in Africa fell to its lowest level in more than decade last year despite the continent's huge potential, experts said Wednesday at the COP27 climate conference.

Only $2.6 billion of capital was rolled out for new wind, solar, geothermal and other renewable power-generating projects in 2021, the lowest level of funding in 11 years, research group BloombergNEF (BNEF) said.

The UN climate summit in Egypt has afforded local rights defenders rare visibility, but some fear a backlash after global attention shifts away from President Abdel Fattah al-Sisi's regime.

With little promise of speedy united action to tackle the climate crisis, many headlines out of COP27 have focussed on the plight of Egyptian activists, most prominently jailed dissident Alaa Abdel Fattah.

"We needed this," Hossam Bahgat, founder of the Egyptian Initiative for Personal Rights, said Tuesday at a press conference that he noted would have been "impossible" in Cairo.

Iran's top security official Ali Shamkhani called for dialogue to end the war in Ukraine during a meeting Wednesday in Tehran with his Russian counterpart Nikolai Patrushev.

Patrushev later met with President Ebrahim Raisi, who said that "broadening the scope of the war and its escalation are a source of concern for all countries," according to official news agency IRNA.

The meetings come after Kiev and its Western allies accused Russia in recent weeks of using Iranian-made drones to carry out attacks in Ukraine. Tehran denies the allegations.