At least 15 people who registered for Saudi Arabia’s delegation to the COP28 climate conference in Dubai appear to be undeclared employees of the Saudi state oil company, according to research by an environmental nonprofit.

Saudi Arabia, the world’s second-biggest oil producer, was one of the main countries opposing an aggressive commitment to phase out fossil fuels at the United Nations-led summit. Saudi Arabia and other large oil-producing nations have traditionally held sway in nixing potential agreements on reducing oil, gas and coal, which when burned cause climate change.

This year, however, negotiators went into extra time before approving an agreement that calls for a transition away from fossil fuels for the first time, though critics say it is filled with loopholes.

New rules for this year’s talks required registrants to disclose their affiliation, a move aimed at improving transparency. Activists have long questioned the presence of fossil fuel producers at the talks, although the companies and many experts have said it makes sense for them to participate given their role in the emissions that cause climate change.

Global Witness reported that at least 14 members of the Saudi delegation had names that matched employees of the state oil company, Saudi Aramco. The Associated Press independently verified the nonprofit’s work. Two more registrants declared elsewhere — but not in their conference registration — an affiliation to Aramco. One of those was a board member.

AP earlier reported that at least 1,300 employees of organizations representing fossil fuel interests registered to attend this year’s talks. Aramco had not declared any delegates to this year’s conference, according to the AP research.

Aramco declined comment to AP. The United Nations Framework Convention on Climate Change, which oversees the conference, did not respond to a request for comment.

Aramco gets some 99% of its revenues from fossil fuels, according to research by the nonprofit Urgewald. It’s not clear what role the apparent Aramco employees would have played within the Saudi delegation.

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The UNFCCC secretariat asked delegates this year to declare their employer, as well as their relationship to the delegation they are guests of. It said participants could opt out of declaring the relationship but made no mention of opting out of declaring an affiliation.

The Global Witness count would make Aramco one of the larger fossil fuel companies to have registered attendance. Russian state-owned Gazprom, the world’s second-leading producer of oil and gas, declared at least 16 employees as attendees at this year’s climate conference.

Aramco employees on the Global Witness list included CEO Amin Nasser, senior vice president Fahad Al-Dhubaib and director of international affairs Nesa Subrahmaniyan.

“The world’s largest oil company snuck executives into COP28 without disclosing their interest,” Jonathan Noronha-Gant, senior campaigner at Global Witness, said. “We need to rid COPs of oil industry influence.”

Global Witness said it reviewed the 136 Saudi registrants who said they were affiliated to the country’s Ministry of Energy, to look for names of people employed by Aramco. Saudi Arabia’s total delegation has 478 people; the nonprofit did not review the entire delegation.

COP24, held in 2018, was the last year Aramco disclosed in the UN attendance rolls that it had sent staff.

Saudi Arabia hailed the deal announced Wednesday as a success. The country did not respond to requests for a comment.