Nearly 400 millionaires and billionaires from 24 countries are calling on global leaders to increase taxes on the super-rich, amid growing concern that the wealthiest in society are buying political influence.

An open letter, released to coincide with the World Economic Forum in Davos, calls on global leaders attending this week’s conference to close the widening gap between the super-rich and everyone else.

The letter, signed by luminaries including the actor and film-maker Mark Ruffalo, the musician Brian Eno and the film producer and philanthropist Abigail Disney, says extreme wealth is polluting politics, driving social exclusion and fuelling the climate emergency.

“A handful of global oligarchs with extreme wealth have bought up our democracies; taken over our governments; gagged the freedom of our media; placed a stranglehold on technology and innovation; deepened poverty and social exclusion; and accelerated the breakdown of our planet,” it reads. “What we treasure, rich and poor alike, is being eaten away by those intent on growing the gulf between their vast power and everyone else.

“We all know this. When even millionaires, like us, recognise that extreme wealth has cost everyone else everything else, there can be no doubt that society is dangerously teetering off the edge of a precipice.”

According to Forbes, Donald Trump assembled the richest cabinet in US history last year after being re-elected as president, with an estimated joint worth last August of $7.5bn (£5.6bn).

A poll conducted for the Patriotic Millionaires group, who campaign for higher taxes on the super-rich, found that 77% of millionaires from G20 countries think extremely wealthy individuals buy political influence.

The survey, of 3,900 people in G20 countries with more than $1m in assets, excluding their homes, also found that three-fifths think Trump has had a negative impact on global economic stability (the poll was conducted before the US president threatened new tariffs at the weekend against European countries if a deal to acquire Greenland was not reached).

More than 60% of those surveyed were concerned that extreme wealth was a threat to democracy. Two-thirds supported higher taxes on the super-rich to invest in public services, with only 17% opposed.

The development charity Oxfam reported this week that a record number of billionaires were created last year, taking the global total to more than 3,000 for the first time.

“Last year the rise in billionaire wealth was unprecedented,” said the executive director of Oxfam International, Amitabh Behar.

“The super-rich are being given complete free rein. It is beyond comprehension that the richest 1% now own three times more than the world’s total public wealth combined.

“It’s a stark indictment that illustrates just how nonsensical the gulf now is between oligarchs and the rest of humanity. Governments must implement taxes on the super-rich now and prioritise reducing inequality. The world cannot continue on this obscene trajectory.”