Three students at the Cambridge University have gone on hunger strike as part of an increasingly bitter campaign to stop the university investing in fossil fuel companies.

The move by the three undergraduates is part of an ongoing divestment campaign at the university that has been supported by hundreds of academics and scientists – including Sir David King, until recently the UK’s permanent special representative for climate change, Thomas Blundell, the former president of the UK Science Council and the author Robert Macfarlane.

The university, which campaigners estimate has £377m invested in fossil fuel firms both directly and indirectly, is expected to take a decision on its future investment strategy at the university’s council meeting on Monday.

A spokesperson said: “The council will consider all aspects of divestment, including ethical issues, in its response to the working group on divestment’s final report ... The objective, as the report sets out, is to promote and execute urgent and tangible action to deliver a carbon neutral future. The university is already taking steps that must be further expanded in the areas of its investments, research, education, estate and policy decisions.”

But student Sam Warren-Miell, one of the hunger strikers, said the university must fully divest from all fossil fuels.

“We have exhausted all democratic channels to full divestment and so we are left with no other option but direct action.

“University council have an opportunity on Monday to show real leadership. We hope that by taking this action, we will encourage them to make the right decision on Monday and be on the right side of history.”

The divestment campaign has been backed by the former archbishop of Canterbury Rowan Williams and the Cambridge MP Daniel Zeichner. This week students chalk-sprayed the university administration building as the protests escalated.

Cambridge Zero Carbon Society use chalk spray to protest against the university’s investment in fossil fuels on 14 May. Photograph: Courtesy of Cambridge Zero Carbon Society

The university says its investments were reviewed in 2016, when it found it had “no directly held exposure to the most pollutive industries, such as thermal coal and tar sands, and no expectation of having any such exposure in the future.”

But Ben Margolis, another of the hunger strikers said: “Unless decisive action is taken quickly, we’re heading for a global temperature increase of over 2C which will be a catastrophe for the whole of humanity in our lifetimes, and we must also acknowledge that climate change is already having a devastating impact on millions of people in the global south today.

“Every day that the university continues to invest in fossil fuels, directly or indirectly, it is complicit in their suffering, and this is why we will not stop the university commits to full divestment.”