(AFP) - Saudi Arabia will host the COP16 UN conference on land degradation and desertification next week as the top oil exporter pitches itself as an environmental defender despite criticism of its role at climate talks.

UN Secretary-General Antonio Guterres has called the meeting for the United Nations Convention to Combat Desertification (UNCCD) a "moonshot moment" to protect and restore land and respond to drought.

Activists accused Saudi Arabia, the world's biggest oil exporter, of trying to water down calls to phase out fossil fuels at last week's COP29 UN climate talks in Azerbaijan.

However, the subject of desertification is close to home for the Gulf kingdom, which has one of the biggest deserts on the planet.

"We are a desert country. We are exposed to the harshest mode of land degradation which is desertification," deputy environment minister Osama Faqeeha told AFP.

"Our land is arid. Our rainfall is very little. And this is the reality. And we have been dealing with this for centuries."

Land degradation disrupts ecosystems and makes land less productive for agriculture, leading to food shortages and spurring migration.

Land is considered degraded when its productivity has been harmed by human activities like pollution or deforestation. Desertification is an extreme form of degradation.

- 'Under the radar' -

The last gathering of parties to the convention, in Ivory Coast in 2022, produced a commitment to "accelerating the restoration of one billion hectares of degraded land by 2030".

But the UNCCD, which brings together 196 countries and the European Union, now says 1.5 billion hectares (3.7 billion acres) must be restored by decade's end to combat crises including escalating droughts.

Saudi Arabia is aiming to restore 40 million hectares of degraded land, Faqeeha told AFP, without specifying a timeline. He said Riyadh anticipated restoring "several million hectares of land" by 2030.

So far 240,000 hectares have been recovered using measures including banning illegal logging and expanding the number of national parks from 19 in 2016 to more than 500, Faqeeha said.

Other ways to restore land include planting trees, crop rotation, managing grazing and restoring wetlands.

The COP29 climate talks yielded a hard won $300 billion climate finance deal that poorer nations most at risk of worsening disasters dismissed as insultingly low.

UNCCD executive secretary Ibrahim Thiaw told AFP he hoped COP16 would result in an agreement to accelerate land restoration and develop a "proactive" approach to droughts.

"We have already lost 40 percent of our land and our soils," Thiaw said.

"Global security is really at stake, and you see it all over the world. Not only in Africa, not only in the Middle East."

Faqeeha said he hoped the talks would bring more global awareness to the threat posed by degradation and desertification.

"If we continue to allow land to degrade, we will have huge losses," he said.

"Land degradation now is a major phenomenon that is really happening under the radar."

Saudi Arabia's high oil production, resulting in eye-watering profits for oil giant Aramco, routinely draws the ire of climate activists.

But its exposure to desertification could give it more credibility during the Riyadh talks.

"With the desertification fight, (Saudi Arabia is) not necessarily directly contributing to the problem, whereas with climate change, it obviously is," said Patrick Galey, senior fossil fuels investigator for Global Witness.

"Saudi Arabia can, with some legitimacy, claim to be standing up for the little guy when it comes to desertification, because it is directly affected."

- Freedom of speech -

Thousands of delegates have registered to attend the December 2-13 talks in Riyadh including "close to 100" government ministers, Thiaw said.

French President Emmanuel Macron is due to attend the One Water Summit, taking place on the sidelines of COP16 on December 3.

Saudi Arabia's de facto ruler, Crown Prince Mohammed bin Salman, has been criticised for mounting repression even as the kingdom pursues head-spinning social reforms intended to lure tourists and investors.

As a UN-organised event, civil society including campaigners will be able to take part, although it was not clear if protests -- a rarity in the kingdom -- would be allowed.

Saudi Arabia is hoping for strong, "constructive" civil society participation in COP16, Faqeeha said.

"We are welcoming all constructive engagement," he told AFP, while Thiaw said all groups would be welcome to contribute and express themselves.

"According to UN rules, of course there are rules of engagement, and everybody is guaranteed freedom of speech," Thiaw said.

© Agence France-Presse