The volume of forex trading is far greater than the size of foreign currency reserves held by any country.

The size of forex trade has played its part in the currency crises of emerging nations over the past year.

The exact figure, $1,490bn, or $1.49 trillion, is 26% higher than when the BIS, which represents central banks, last measured flows in 43 different countries three years ago.

Centred in London

Almost a third of all forex trading occurs in London, by far the world's largest centre, with New York and Tokyo second and third.

US dollar and yen most traded

At current values, transactions involving US dollars on side of the trade accounted for 87% of forex business. The Japanese Yen was the second-most traded currency.

However, less than half the transactions were simple 'spot' deals, the immediate purchase of currency for commercial transactions.

Most forex trading is on the futures market where currency buyers undertake to buy at a set price at a specified date in the future.

Futures gambling

Foreign exchange futures allow companies to plan their import, export and foreign investment operations with the certainty of knowing what will be the value of the currencies they trade in.

George Soros: forex speculator

However, increasingly the forex futures market is home to rich individuals and 'hedge funds' who speculate against currency movements attempting reap windfall gains.

George Soros is the most high-profile example of such currency speculators.

The advent of the euro next year is expected start to stem the sharp increases in forex dealings as eleven European currencies consolidate into one over the next three years.

Global crises

The figures shed some light on how financial crises began in emerging economies over the last year.

The ability for massive daily foreign currency flows to take place made possible the almost overnight collapses of the currencies of countries like Thailand, Indonesia and Russia.

As confidence in the economies of these countries fell away, demand for their currencies fell as investors took their capital out or stopped bringing it in.

Governments had tried to buy their own currencies to underpin their value but couldn't keep up with the sellers.

When they stopped their own forex activity, the forces of demand and supply saw the baht, rupiah and rouble in turn crash in value deepening the crisis of confidence and economic slowdown.