Wealth used to be a man's world, but the gap between the sexes is narrowing when it comes to money, a new report shows.

In Britain, the number of female millionaires has been rising on the back of social trends - such as inheritance and the rapidly climbing divorce rate - and they now make up nearly half of all millionaires in the UK, according to independent market analyst Datamonitor.

On top of that, a new generation of women have started to prosper in their own right, and female entrepreneurs are increasingly growing in number.

While a male millionaire's wealth has increased by an average 9.2 per cent over the past eight years, the worth of a female millionaire has ballooned by 53.9 per cent, Datamonitor found.

The British study showed that in 1998, the average male millionaire was worth ¡ê2.71 million (AUS$6.51m), while the female equivalent owned just ¡ê1.28m.

But by 2006, the gap had narrowed to ¡ê2.96m for male millionaires and ¡ê1.97m for women.

Women make up about 46 per cent of Britain's 376,000 millionaires - and their number is growing by almost 11 per cent a year.

Some 3800 British women owned liquid assets of more than ¡ê5m, Datamonitor said.

The number of women of "high net worth" status (classified as those with onshore liquid assets of more than ¡ê200,000) overtook men in 2005 - with 448,100 rich women compared to 429,300 men

Nine of the world's fifty richest people are women.

The richest self-made woman in the world is Rosalia Mera (61) of Spain, who is worth approximately $2.4 billion.

She started off making gowns and lingerie in her home. Her business eventually grew into the apparel manufacturer Inditex, which sold $6 billion worth of clothes last year.