AT precisely 2.30pm on Thursday a newsflash hit the vast information screens in the pit at the International Petroleum Exchange (IPE) near Tower Hill in London. Within seconds the lull in the afternoon’s trading was shattered.

More than 100 traders in multi-coloured jackets swarmed into the small pit, shouting and waving papers, while straining to hear instructions from colleagues on telephones just a few steps away.

The Organisation of the Petroleum Exporting Countries (Opec) had announced it would raise oil output by 2m barrels a day and by a further 500,000 barrels a day on August 1.

The amount was below expectations and, after a week in which oil prices hit highs of $42 a barrel, it caused more worries about the strength of the world’s oil supplies. But at the IPE, where they trade oil futures — the right to buy oil at a set price and time — the news created a flurry of demands from clients.

As usual, there were refiners and big companies that depend on oil, such as airlines, wanting to buy the futures and gain the stability, if not the comfort, of knowing the price they will pay for oil in the coming months.

But the traders were also acting for many financial investors, the market’s new and rapidly growing breed of clients. In recent months investors, including pension funds, hedge funds and individuals, have, as one trader put it, “discovered the real black gold is oil futures”.

More than $20 billion (£11 billion) has been piled into oil futures over the past year.

In 2003, investors — or speculators as they are known — accounted for 3.5% of the futures market. In recent weeks this figure has leapt to 20%, the highest level ever.

Experts say the rate at which money is flooding into the market is pushing up the price of oil by as much as 33%. David Kitson, global head of energy at JP Morgan, said: “Traditionally the oil market has been driven by simple supply and demand. Increasingly, it is being driven by investors and this could account for about $10 a barrel.”

Jeff Currie of Goldman Sachs said: “The premium added to the oil price because of speculators is about $7 a barrel.”

The soaring oil price may be bad news for consumers, from big companies to motorists, but it has made millionaires out of many who saw the rise coming.

Simon Ramsay, 43, a former City trader, has collected some $100,000 in the past few weeks from cashing in a few of the futures contracts he has amassed.

“Last year I didn’t really know anything about oil futures,” said Ramsay. “Then a former colleague told me about some research he had found which convinced me the oil price was only going to go up.

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