The collapse of US oil trader SemGroup is said to have played a role in the dramatic decline in the price of crude oil over the past 10 days.

US crude is trading today down six cents at $124.38 while Brent is down 11 cents to $125.18.

Prices have been falling steadily since 11 July when US crude hit a record $147.27 a barrel.

The drop has been explained by a stronger dollar that has limited the appeal of commodities as a hedge against inflation and lower petrol usage among consumers as costs have risen.

But the Wall Street Journal says SemGroup's collapse has also played its part.

The company filed for bankruptcy protection with losses of at least $2.4 billion (£1.20 billion) when its hedging strategies went wrong.

It had taken out short positions, but when oil prices rose SemGroup moved to cover them by taking out equivalent long positions.

In the end SemGroup did not have collateral for its growing bets and sold its futures account to Barclays Capital.

But the Journal says the massive long positions added to other factors driving up oil prices.

SemGroup's rapid exit from the market removed a big upward pressure just as other factors also helped bring down the price.

• There are 90 billion barrels of oil and vast quantities of natural gas in the Arctic Circle, according to a report by the US Geological Survey.

So far 40 billion barrels have been discovered in the region.

By comparison, US oil reserves stand at 22 billion barrels and its production level at 1.6 billion barrels a year.

Most of the Arctic reserves are located offshore.

As well as crude oil there is 1,670 billion cubic feet of gas and 44 million barrels of natural gas liquids.