Researchers at UK universities are bracing themselves for sanctions affecting science partnerships with Russia, including in climate science and space research, as the government seeks to isolate Vladimir Putin over the invasion of Ukraine.

Simon Marginson, a professor of higher education at the University of Oxford, said most academics would support a research boycott with heavy hearts and concerns for Russian colleagues.

“All the Russian academics I know oppose the war. The internal situation in Russia will get nastier and they will need solidarity, so there is a case for maintaining ties,” he said.

Germany announced that all collaboration with Russia on education and research was being halted immediately. Its ministry of education said Russia had “turned its back on the international community” by invading Ukraine and was committing a “grave breach of international law” with no justification.

This week George Freeman, the UK science minister, said he had ordered “a rapid review” of all Russian beneficiaries of UK science and technology funding.

Experts say possible sanctions could include a ban on British academics collaborating with Russian scientists, the freezing of any joint funding, and the exclusion of Russian scientists from reading or publishing in international scientific journals.

Prof Colin Riordan, the vice-chancellor of Cardiff University, a member of the prestigious Russell Group, said some Cardiff academics had withdrawn from events in Russia of their own accord. If the government were to tell his university to cut ties with Russia, it would do so because of the “bigger things at stake”.

But he said the government should be careful about any blanket ruling banning all collaboration with Russian academics. “We need to distinguish between the government and citizens of Russia who find themselves in an extremely difficult position,” he said.

Prof Steve West, the president of the vice-chancellors’ group Universities UK, told the Guardian: “I think we have to expect science sanctions. The position of universities is always that scientific collaboration and research are a vital global endeavour. However, what is happening is a challenge on democracy and the safety and stability of the free world.”

Academics in Russia, thousands of whom have signed open letters opposing the war, say their international relationships are fracturing. They say academics from across Europe are cancelling trips and pulling out of partnerships.

Almost 4,000 academics, students and graduates of the prestigious Moscow State University, Russia’s oldest university, have signed a letter saying they “categorically condemn the war that our country unleashed in Ukraine”.

The letter says: “There is no room for euphemisms or excuses. War is violence, cruelty, death, loss of loved ones, powerlessness and fear that cannot be justified by any goal.”

Another condemnatory open letter on Thursday had been signed by more than 15,000 Russian academics and students.

A senior Russian scientist, who asked not to be named for fear of reprisals, said some science leaders had been accused of “betraying the motherland” by speaking out against the war. Many were afraid to sign the letters because of a “culture of fear”.

“People in the west do not fully understand the pain we feel,” he said. “It is like England invading Scotland. Many of us have relatives in Ukraine or were born there.”

He said he knew academics in Russia who had written privately to research partners in the UK and other countries, stressing that they did not support the invasion of Ukraine, and expressing hope that they might find a way of continuing to work together.

A Russian scientist in St Petersburg, who said he had been chased by riot police this week, tweeted: “I’m so disgusted with rejection letters, invitation cancellations, grant withdrawals against Russian scholars from Western academics who fight Putinism by attacking those who have suffered from it for decades.”

A Russian climate scientist based at a leading Russell Group university in the UK, speaking on condition of anonymity, said his field work, which was based in Russia and involved Russian scientists in different disciplines, looked likely to grind to a halt. A joint expedition he had been planning with colleagues in Moscow has been cancelled. “Russia is such a huge territory and we will lose so much empirical data. This will be a really big blow for climate science.”

The scientist, who said he was “appalled and devastated” by the invasion of Ukraine, added: “The majority of academics in Russia are not fans of the current regime, and of course sanctions will strike right at them.”

Paul Nightingale, a professor of strategy at Sussex’s University’s science policy research unit, said measures should be adopted that would “be brutal and would achieve the aim of turning more people against Putin”.

In addition to curbs on collaboration and publishing, Britain and the US could consider offering five-year working visas to every Russian with a PhD, he said, to prompt a brain drain from the country, although he added that this could damage hopes of Russia becoming a more liberal society in the future.

Nightingale, formerly a director of special projects at the UK government’s Economic and Social Research Council, said he was in favour of sanctions to isolate Putin in the coming weeks, but they must be imposed carefully to avoid killing the possibility of useful academic diplomacy.

“Even during the worst of the cold war, American, European and Russian scientists would work together on important problems,” he said. “Those social networks provided really important back channels for communication.

“Unfortunately the people we would be hurting most in trying to damage Putin would be our friends.”

Prof Isak Froumin, the head of the Institute of Education at the Higher School of Economics in Moscow, said global science had been very important to Putin’s regime. Until 2018 the Russian government was pushing universities hard to play more of a role in global science by collaborating with researchers abroad and publishing in international journals, he said. “International collaboration in science was considered absolutely necessary and prestigious.”

He added: “The idea that might be all broken is a great shock to scientists.”

Prof James Wilsdon, the director of the Research on Research Institute, based at Sheffield University, said the UK government was likely to focus sanctions on areas with strategic security implications for Russia, including climate science in the arctic and space research.

He warned that in the longer term ministers must be careful not to “choke off the good”. “Links in science are a very important part of maintaining what spark of freedom there is in Russia,” he said.