Oil rose to $50 a barrel for the first time since January on Thursday after a move by the Federal Reserve to buy government bonds hit the dollar and revived hopes the U.S. economy could soon begin its recovery.

It's a combination of a drop in the U.S. dollar and the Fed's move that has pushed up oil prices, said David Moore, a commodity strategist at the Commonwealth Bank of Australia.

But I suspect more of it is probably on hopes that U.S. policy stimulus would help turn the economy around, or at least stabilize it.

U.S. crude for April was up $1.97 a barrel at $50.11 by 1101 GMT (7:01 a.m. EDT), hitting $50 for the first time since January 6 and earlier rising as high as $50.25. London Brent for May delivery

rose $1.99 to $49.65.

Some other commodities also advanced as the Fed's plan sparked hopes demand may improve. Copper was up more than 5 percent at a four-month high.

The $50-mark has been the top of oil's trading range so far in 2009. A close above that level is needed to increase the prospect of a further rally, said analysts who use past price moves to predict future direction.

The dollar edged lower against a basket of currencies on Thursday, after posting its biggest daily fall since 1985. A weak dollar can boost investor demand for oil and other commodities priced in the U.S. currency.

(Additional reporting by Fayen Wong; Editing by James Jukwey)