The world's richest people have failed to escape the ravages of recession with billionaires seeing their wealth shrink by almost a quarter in the last year, business magazine Forbes has said.

Its annual list revealed that nine in ten billionaires lost money over the past 12 months, with the average hit being 23% of total wealth.

Britons are among the biggest losers on the list - Sir Richard Branson and Sir Philip Green both saw their fortunes slashed, it is suggested.

Meanwhile, two-thirds of Chelsea owner Roman Abramovich's fortune was wiped out last year. In a sign that the global economic downturn is hitting the highest earners, the Forbes list is smaller than last year. In 2008 there were 1,125 billionaires. This year, the number of uber-rich had shrunk to 793 - a drop of almost a third.

Bill Gates has regained his position as the world's richest man, with a personal fortune of 40 billion dollars (£29 billion). Despite losing 18 billion dollars during the year, the Microsoft founder leapfrogged Warren Buffett who took a 25 billion dollar (£18 billion) hit over the same period. Mr Buffett dropped to second place with a not-so-meagre 37 billion dollars (£26.8 billion).

New York Mayor Michael Bloomberg is the only person in the top 20 to see his wealth increase. His net worth went up by 4.5 billion dollars (£3.3 billion) following a re-evaluation of his financial data company.

Britain boasts 25 billionaires - down from last year's 35. Duke of Westminster, Gerald Grosvenor, again led the way for the UK. His 11 billion dollars (£8 billion) - down from 14 billion dollars (£10.2 billion) last year - saw him placed 29th in the list of the world's richest billionaires.

Virgin boss Sir Richard Branson came in at 261, with his fortune shrinking from 4.4 billion dollars (£3.2 billion) to 2.5 billion dollars (£1.8 billion) during the year. Retailer Sir Philip Green also had a painful financial year. He lost 3.6 billion dollars (£2.6 billion), with his wealth now estimated at 4.8 billion dollars (£3.5 billion).

Newcastle FC owner Michael Ashley saw his fortune tumble by 1.4 billion dollars (£1 billion) over the last year to 1.1 billion dollars (£800 million) The loss was dwarfed by fellow football boss Roman Abramovich. The Chelsea owner lost a staggering 15 billion US dollars (£10.9 billion) during the year, seeing his personal fortune drop to 8.5 billion dollars (£6.2 billion). Mr Abramovich is one of 28 billionaires living in London, according to the Forbes list.

Harry Potter writer J K Rowling remained on the billionaires' list. Her one billion dollars (£725 million) - unchanged from last year - saw her come in at 701.