ZURICH (Reuters) - The wealth held by the world's billionaires jumped by about 17% over the past year, as significant gains among the super rich in the United States more than offset a decline in China, Swiss bank UBS said on Thursday.

The UBS Billionaire Ambitions Report for 2024 said the total number of billionaires had risen to 2,682 from 2,544 a year earlier, and their worth to $14 trillion from $12 trillion. In 2015, their total wealth stood at $6.3 trillion.

According to the World Bank, the globe's population was just over 8 billion last year, and its gross domestic product (GDP) about $105.4 trillion, underlining just how much wealth is concentrated in a tiny sliver of humanity.

Most of the year's new billionaires were self-made. The bank's report for 2023 had shown new billionaires acquiring more wealth through inheritance than entrepreneurship.

The latest report, based on a survey of billionaires conducted between June and September and wealth data on the super rich, showed the risk of geopolitical conflict and inflation were their main worries.

The survey also showed that North America was overwhelmingly seen as offering the best investment returns over the next year.

In the United States, the number of billionaires jumped to 835 from 751, led by industrial and tech magnates, with their total wealth climbing to $5.8 trillion from $4.6 trillion.

In mainland China the number of billionaires dropped to 427 from 520, and their wealth to $1.4 trillion from $1.8 trillion. In 2021, there were 626 in mainland China, together worth more than $2.5 trillion, according to previous UBS figures.

Benjamin Cavalli, head of strategic clients at UBS global wealth management, said the decline reflected losses in real estate markets and a drop in the value of firms owned by some of China's wealthiest amid a less certain economic outlook.

India's number of billionaires increased during the past year by over a fifth to 185 and their wealth by more than 40% to almost $906 billion, UBS said.

In Western Europe, Switzerland overtook Britain to become the country with the second-highest number of billionaires after Germany, increasing its total by 10 to 85.

France, with 46 (+12), Germany with 117 (+8), Italy with 62 (+6) and Spain with 27 (+3), all gained billionaires whereas the British total dropped by one to 82, UBS said. The combined wealth of France's billionaires was highest among Europeans.