Home advantage will help Britain to improve on its bumper 2008 medal haul when London hosts the Games next month, a study by economists from business services group PwC said on Thursday.

The United States and China would again be slugging it out for supremacy at the top of the medals table, added the study which weighs factors such as past performance, economic strength and state support for sport.

"Host nations generally 'punch above their weight' at the Olympics, which bodes well for the British team in London," said John Hawksworth, chief economist at PwC, predicting Britain would maintain fourth spot in the medal table behind Russia.

He saw Britain taking an extra seven medals on top of 47 won in China four years ago.

"Home country advantage should on average boost medal share by around two percentage points, which might translate to around an extra 19 medals for Britain in 2012," he added.

"However this needs to be tempered by the remarkable performance for the British team in Beijing that may have seen preparations for London 2012 already starting to bear fruit in areas such as cycling, rowing and sailing."

In Beijing, China won 51 golds to top the overall medal table, while the United States won gold 36 times.

"In general, the number of medals won increases with the population and economic wealth of the country, but less than proportionately," said Hawksworth.

"David can sometimes beat Goliath in the Olympic arena, although superpowers like the US, China and Russia continue to dominate the top of the medals table."

The study highlighted India as a significant underperformer relative to its size and economic output, but noted that India focused on sports not in the Games such as cricket.