The wealth of the world’s 3,000 billionaires has surged by $6.5tn (£4.8tn) in real terms over the past decade, according to Oxfam, equivalent to 14.6% of global output.

In total the richest 1% of the global population has gained at least $33.9tn in real terms, which the charity said was “enough to end annual global poverty 22 times over”.

The figures come as various governments face growing calls to introduce a wealth tax on the international elite.

In the UK, the number of billionaires has grown sharply, from 15 in 1990 to 165 in 2024, according to separate figures from the Equality Trust, which found their average wealth rose by more than 1,000% over the same period. Billionaires pay “effective tax rates close to 0.3% of their wealth, well below what average workers contribute”, Oxfam said.

The charity called on the UK to work with other governments to oppose “extreme inequality”, with private wealth growing eight times faster than the net wealth of governments between 1995 and 2023.

Rachel Noble, a senior policy adviser at Oxfam, said: “This government is in danger of careering way off course on international development if it does not recommit to proven approaches to tackle poverty through public investment and fair taxation.

“The government must fairly tax the trillions of pounds that are locked away in the bank accounts of the super-rich and prioritise the fight against inequality, gendered oppression and the climate crisis.”

Last year Spain, Brazil, Germany and South Africa signed a motion at the G20 for a minimum 2% tax on the super-rich to reduce inequality and raise public funds. Forecasts on its potential impact vary, but a study by the leading French economist Gabriel Zucman found that it could net up to $250bn in extra revenue.

The four countries have called on other governments to support the campaign, saying that a levy on the ultra-wealthy would complement negotiations on the taxation of the digital economy and ongoing efforts to bring in a global minimum corporate tax of 15% for multinational businesses.

Ministers from Spain, Brazil, Germany and South Africa have argued that there would need to be steps to counter the use of tax havens, and a levy would be designed to prevent evasion by billionaires who choose to live in, for example, Monaco or Jersey, but make their money in bigger economies such as the UK or France.

Spain’s economy minister, Carlos Cuerpo, said during a visit to London last November that the world’s richest countries needed to “be brave”, saying recent elections had shown citizens were demanding “redistribution of wealth”.

A survey by Oxfam found that 86% of people supported paying for public services by “closing loopholes” that allow wealthy individuals and large corporations to use tax havens.

The government was approached for comment.