The price of oil has hit its highest level of the year, boosted by sharp rises in Chinese stocks and rising shares on Wall Street.
The price of US crude rose to $74.15 a barrel before settling at $73.89, a gain of 98 cents. London Brent was up 86 cents at $74.19.
The oil price hit $147 a barrel last July and fell below $74 last October, a level it has not breached since.
Worldwide oil prices have been extremely volatile this year.
Prices have been affected as much by sentiment as by fundamentals of demand and supply.
Ben Bernanke, the chairman of the Federal Reserve, said that prospects for a return to growth in the near term appeared good in the US and abroad.
US shares traded higher - with the Dow Jones index rising 1.7% to 9,506 - after Mr Bernanke's speech and on better-than-expected figures for sales of existing homes.
Sales rose by 7.2% in July to an annual rate of 5.24 million homes.
"The significant rise in the oil price in the first half of the year is due in large part to a recovery in investment by financial investors," said Eugen Weinberg at Commerzbank.