Brent crude rose $3 on Wednesday after the U.S. Federal Reserve's promise to extend near-zero interest rates for two more years weighed on the dollar and helped reverse a steep slump in oil.

The Fed's unprecedented step prompted investors to get back into riskier assets that use the dollar as a funding currency, leading Wall Street <.SPX> to post its best one-day gain in more than two years and copper soar more than 2 percent.

Prices rose even though implied crude demand in July in the world's No. 2 consumer, China, was the second-lowest this year.

The economic reality is that if the U.S. enters into a recession, then no matter how strong growth in China is, China will be negatively impacted, said Victor Shum, an analyst at Purvin and Gertz. What we are seeing is a relief rally after the Fed announced measures to help support the economy.

Brent crude for September rose as much as $105.67 a barrel and traded at $104.77 by 0356 GMT. It ended post-settlement trading up $1.76 at $105.50 a barrel, after settling at $102.57, down $1.17, the lowest since February 18 and sliding as much as 15 percent in a week.

U.S. oil rose as high as $82.43 a barrel and traded at $81.45, after rallying to end post-settlement trading at $82.14. It settled at $79.30, down $2.01, having reached $83.05 after falling to $75.71, the lowest since September 2010. Volumes were strong, with Brent and U.S. crude trading more than 50 percent above their 30-day averages.

The U.S. dollar stayed under pressure in Asia on Wednesday, with the Australian dollar soaring nearly five full U.S. cents to above $1.0400 at one stage, recouping about half of the steep falls seen recently.

Hopefully, this is it for the oil market after investors who took too much risk got out, said Tony Nunan, a risk manager with Tokyo-based Mitsubishi Corp.

There are a lot of supply side issues to keep prices supported. The Libya crisis is going nowhere, and the key really is to see what is going to happen in China.

China's implied oil demand in July rose 7.7 percent over a year earlier, picking up from June, which marked the slowest growth in more than two years, according to Reuters calculations based on preliminary government data.

OIL DEMAND

Investors are watching the world's No. 1 commodity buyer to see if its thirst for a raft of products could rise on an expected stockbuilding spree.

The Organization of the Petroleum Exporting Countries and the U.S. Energy Information Administration cut demand growth forecasts for 2011 in separate monthly reports.

OPEC's expected oil demand growth increase for 2011 was lowered by 150,000 barrels per day (bpd) from the previous report to 1.21 million bpd. The EIA cut its 2011 demand growth forecast by 60,000 bpd but raised its 2012 forecast.

The American Petroleum Institute, in a report late on Tuesday, said U.S. domestic crude stocks fell 5.2 million barrels last week.

That compares with an expanded Reuters poll that forecast crude stockpiles to have risen for the third straight time last week as releases from the Strategic Petroleum Reserve kept moving into commercial inventories.

Twelve analysts polled expected a build in crude stocks for the week to August 5, with the average forecast coming in at 1.5 million barrels.

This is a positive for the oil market, said Nunan. Especially given that stocks were supposed to rise after the release of strategic reserves.

(Reporting by Manash Goswami; Editing by Clarence Fernandez)

China Libya Energy OPEC