Developed and emerging economies must use a summit this weekend to forge an international agreement to increase wealth taxes on the global rich, campaigners have said. In an open letter to the G20 before its meeting in Delhi, the group of almost 300 millionaires, economists and politicians say urgent action is needed to prevent extreme wealth “corroding our collective future”. The letter, whose signatories include the Disney heiress Abigail Disney and the artists Brian Eno and Richard Curtis, urges the G20 to demonstrate the same global cooperation it showed in ensuring multinational companies pay a minimum level of tax to agree collectively to tax wealth. With deep divisions between members of the G20, little is expected of this weekend’s summit, but those pushing for a wealth tax said it was time for leaders to listen to public opinion. The letter says: “Much work has already been done. There is an abundance of policy proposals on wealth taxation from some of the world’s leading economists. The public wants it. We want it. Now all that’s missing is the political will to deliver it. It’s time for you to find it.” The letter, organised by Patriotic Millionaires, the Institute for Policy Studies, Earth 4 All, Millionaires for Humanity and Oxfam, says taxing wealth more heavily would shrink “dangerous levels of inequality.” According to the campaigners, the combined wealth of those with more than $50m (£40m) in assets has more than doubled to $11.8tn, and only four cents in every dollar of tax revenue comes from wealth taxes. The UK chancellor, Jeremy Hunt, has no plans for a wealth tax and Rachel Reeves, the shadow chancellor, said last week that an incoming Labour government would not introduce one either. Julia Davies, the impact investor and a member of Patriotic Millionaires UK, said: “Given the woefully disappointing lack of political support for taxing extreme wealth here in the UK, international cooperation is even more important. “Taxing the very richest, those who can most afford it, is a back-to-basics policy when it comes to economic common sense – and yet no major political party has the drive or the decency to get on with the job. It’s as though they are more interested in the politics of an endless race to the bottom for our country, rather than making plans to actually invest in our public good.” Other signatories include the US senator Bernie Sanders, the former UN general assembly president Maria Espinosa, and the economists Gabriel Zucman, Jayati Ghosh, Kate Raworth, Joe Stiglitz, Lucas Chancel and Thomas Piketty. The letter says the G20 – made up of the G7 group of rich countries with leading emerging market nations such as China, India, Brazil and Indonesia – should collectively agree to raise taxes on rich individuals and to stop tax competition and avoidance by the super-rich. Katy Chakrabortty, Oxfam’s head of policy and advocacy, said: “The chorus of voices is surely growing too loud now for politicians to continue to ignore. The world is at a critical juncture; fairer taxation to address the cost of living and climate crises is supported by millionaires and the public alike. It’s high time for governments to act.”