The world has never had so many rich people and their investments in soaring stock markets have made them wealthier than ever recorded, according to a study published on Wednesday.

The number of "high net worth individuals" (HNWI) -- defined as people with liquid assets of at least $1 million -- rose by 5.1 percent last year to 22.8 million, according to consulting firm Capgemini.

Their total wealth reached $86.8 trillion in 2023, a 4.7 percent increase from the previous year, according to the annual World Wealth Report.

The number of HNWI and their total wealth are the highest since Capgemini began the annual study in 1997.

Their fortunes have risen as stock markets have surged: New York's tech-heavy Nasdaq soared 43 percent in 2023 while the broad-based S&P 500 gained 24 percent.

The Paris CAC 40 grew 16 percent while the Frankfurt DAX advanced by 20 percent.

The number of HNWI and their wealth had each fallen by more than three percent in 2022, a year of macroeconomic uncertainty and geopolitical tensions, the report said.

The decline in their wealth was the steepest in a decade as equities fell.

"However, 2023 brought economic growth and improved fortunes for major investment sectors to reverse the falloff," the report said.

"Despite ongoing interest rate uncertainty and rising bond yields, equities surged along with the tech market, fueled by enthusiasm for generative AI and its potential impact on the economy."

Rising wealth and inequality in the world have fuelled debates on making the rich pay their fair share of taxes.

Brazil and France have pressed fellow G20 countries to set a global minimum tax on the world's wealthiest people.