More than 40 senior academics and scientists have vowed not to work with the Science Museum as the row over its financial relationship with fossil fuel corporations escalates.

In an open letter, prominent figures including a former chair of the UN’s climate body, the Intergovernmental Panel on Climate Change (IPCC), and several leading scientists, many of whom have worked closely with the museum in the past, say they are “deeply concerned” about its fossil fuel sponsorship deals and they are severing ties with the museum until a moratorium is announced.

“We are in a climate crisis and should not be doing anything to legitimise those companies that are still driving up emissions by exploring for and extracting new sources of fossil fuels when the science is clear that we need to be leaving them in the ground,” the letter states.

It is the latest blow to the museum, which has faced several resignations and growing protests over its relationship with Shell and a newly announced deal with the renewables company Adani Green Energy, part of the Adani Group, which has major holdings in coal. This week the Guardian revealed how two scientists had refused to allow their work to be featured by the museum.

Jess Worth of the campaign group Culture Unstained, which campaigns to stop fossil fuel sponsorship of the arts, said: “The Science Museum continues to dismiss all critics of its fossil fuel partnerships as wilfully misinformed activists, but in reality it is facing a profound crisis in confidence from the scientific community and losing the public’s trust.”

Last month the climate scientist Prof Chris Rapley, a former director of the Science Museum, resigned from its advisory board, saying he disagreed with its “ongoing willingness to accept oil and gas company sponsorship”.

A few weeks later two trustees – Hannah Fry, a professor in the mathematics of cities at University College London, and Jo Foster, the director of the Institute for Research in Schools charity – resigned from the museum’s board in protest at its deal with Adani.

Fry said the Science Museum was “giving the false impression that scientists believe the current efforts of fossil fuel companies are sufficient to avoid disaster”.

There have been several protests at the museum, most recently when youth activists occupied it overnight.

As well as scientists and academics, many others who have worked with the museum group in the past – as speakers, advisers, contributors to exhibitions or participants in events and festivals – have also signed the letter.

It says that although they have “excellent personal relationships” with “talented and committed members of staff” at the museum, they “can no longer be complicit in the policies adopted by the group’s senior leadership and trustees”.

Dame Mary Archer, the chair of the board of trustees at the Science Museum Group, defended its stance on Friday. “Given the scale of the climate challenge, we reject the argument that we should sever all ties with the energy sector,” she said.

“Energy companies involved with fossil fuels are causing climate change but they also have the skills, money and geographical reach to be a big part of some of the solutions. So where a company is showing a willingness to change, our leadership team believes it is valid to continue to engage, while urging these companies to show more leadership in accelerating the shift to renewables instead of fossil fuels.”

Archer acknowledged there were “robust internal debates” on the issue at the museum and said she fully respected critics who disagreed with the management’s position. “Our door remains open for the dialogue that is integral to our work, both as part of the cultural community and as a science institution, and we’d encourage our critics to consider what is achieved by deplatforming,” she said.

A spokesperson for Shell defended its relationship with the museum, saying tackling the climate crisis would need “unprecedented collaboration between business, government, consumers and civil society”. They said the company had a “comprehensive energy transition strategy” in place.

Adani did not respond to a request for comment.