Thousands of people are expected to gather outside the Treasury in London today to protest against proposed cuts to science funding.

Protesters will argue that science and engineering should not be a "soft touch" for cuts, but a key part of the UK's plans to rebalance the economy and maintain intellectual excellence. The demonstration is organised by the Science is Vital (SIV) campaign, whose supporters include broadcasters Patrick Moore and Tanya Byron, Bad science columnist Ben Goldacre, Cern physicist Brian Cox, several MPs and the president of the Royal Society, Martin Rees.

Cutting support for science, especially when other countries including the US, Germany, India and China are raising their funding, would force Britain out of the premier league in many fields of research, leading scientists have argued.

All government departments have been asked to prepare for cuts of 25% or more in their budgets as part of the government's austerity drive. In 2008/09, the state supplied more than £5bn for universities to carry out curiosity-driven science and up to £1bn could be wiped off annual budgets if the proposed cuts go ahead in the comprehensive spending review later this month.

Today's rally is being organised by the newly-formed Science is Vital (SIV) campaign group, a coalition of research scientists, scientific institutions, teachers, writers and celebrities.

Jenny Rohn, founder of SIV and a cell biologist at University College London, said the idea for the campaign came after she heard business secretary Vince Cable's first speech on science, delivered last month. In the speech, Cable called for scientists to do "more with less" and, speaking on on Today program earlier that morning, mistakenly alleged that 45% of UK science was not of world-class quality. "I've been reluctant to get involved in politics in the past, but it was essentially the last straw," said Rohn. "Scientists are the best possible spokespeople for the fact that cutting funding for science, tech and innovation will actually backfire economically."

So far, around 22,000 people have signed an online petition to protest cuts in scientific research funding and Rohn expects several thousand people attend the rally at the today. "We hope that by showing that scientists are not a soft touch, that there will be a political price to pay if our message goes unheeded by the Treasury."

Many leading scientific organistions have pledged their support to the SIV campaign, including Cancer Research UK, Wellcome Trust, Society for Biology and the Royal Astronomical Society. "As well as scientists and engineers, we've had thousands of ordinary people – from firefighters to teachers to poets and civil servants – signing," said Imran Khan, director of the Campaign for Science and Engineering. "It's going to be a great mix of people from all walks of life who realise that retreating into the past and cutting back our support for science just isn't an option for the UK."

He added: "We're taking our rally direct to HM Treasury, and we want George Osborne to hear our message. British science is a key part of our economy and needs to be supported if we want the economy to grow. Everything we hear suggests that the budgets still haven't been settled, so there's everything to play for. We need the government to realise just how many people care about this issue."

The rally will be addressed by scientists and campaigners including the neuroscientist Colin Blakemore, former Lib-Dem MP Evan Harris, science writer Simon Singh and doctor and writer Ben Goldacre.

"Basic science forms the foundation of everything else that matters," said Khan. "Just look at the [physics] Nobel prize winners Konstantin Novoselov and Andre Geim this week – their work on graphene was blue-sky when they started, and now we hope it could revolutionise materials science and lead to hundreds of applications."