By Gloria Dickie and Kate Abnett

LONDON (Reuters) -Over 100 members of the U.S. Congress and European Parliament called on Tuesday for Sultan al-Jaber to be removed as the designated head of the upcoming COP28 climate talks, saying the oil exec's appointment threatened the integrity of negotiations.

Jaber, who heads the United Arab Emirates oil giant Abu Dhabi National Oil Company, was chosen in January to lead the talks. He also serves as the UAE's ministry of industry and technology as well as its climate envoy.

In a letter sent to U.S. President Joe Biden, European Commission President Ursula von der Leyen and the United Nations, the lawmakers voiced "profound concern" that private sector polluters would be able to "exert undue influence" on the climate negotiations, to be held in Dubai later this year.

"We urge you to ... engage in diplomatic efforts to secure the withdrawal of the president-designate of COP28," they wrote.

Signatories included U.S. Democratic senators Bernie Sanders and Elizabeth Warren. Most EU signatories hailed from the Greens and Left groups.

Scientists and climate activists have expressed dismay at Jaber's appointment, taking it as a sign that big industry has commandeered the global response to the climate crisis.

More than 600 fossil fuel lobbyists were present at the COP27 climate talks held in Egypt last year.

A spokesperson for the COP28 president's office highlighted Jaber's long career in the renewable energy sector.

"We believe that Dr. Sultan’s experience ... working across the energy spectrum, coupled with his experience as a senior global industry leader, are assets that will help drive the UAE’s transformative approach to COP28," the spokesperson said.

Jaber previously told Reuters that he had "no intention" of deviating from the Paris Agreement goal of limiting global warming to 1.5C degrees above pre-industrial levels.

"Keeping 1.5 alive is a top priority and it will cut across everything I do," he said.

This is not the first time that lawmakers have called for Jaber's removal.

Shortly after his appointment, 27 Democratic members of the U.S. Congress sent a letter to top U.S. climate envoy John Kerry urging him to persuade the future U.N. climate summit host to withdraw its pick of Jaber.

Others have thrown their support behind the oil exec. On Monday, EU climate policy chief Frans Timmermans told a European Parliament meeting that "if we want the energy transition to succeed, we have to get the energy companies on board."

"Vilifying them and ignoring them is not going to get the dynamics going in terms of the energy transition, and Dr. Sultan Al Jaber has also a long track record of investing in renewables within his company," Timmermans said.

(Reporting by Gloria Dickie in London and Kate Abnett in Brussels; additional reporting by Maha El Dahan in Dubai; editing by Mark Heinrich)