Optimism that central banks from the United States to Europe may announce measures to prevent their economies from deteriorating further boosted broader markets, from Asian shares to base metals. Most assets are recovering a plunge triggered by a series of weak numbers from China to the United States.
Brent crude gained 32 cents $100.96 a barrel by 0253 GMT, after rising to as much as $101.18 earlier in the session and settling $1.80 a barrel higher on Wednesday. US increased 44 cents to $85.46, gaining for a fourth straight day.
"There are expectations of further monetary easing from the United States and that is making people come back," said Tetsu Emori, a Tokyo-based commodities fund manager at Astmax Investments. "There are many, many factors still out there. There is Greece, there is Europe. All this will keep oil very choppy for the time being."
A crucial support for US crude is $85 a barrel and $100 for Brent, Emori said.
Brent fell below $100 for the first time since October on Friday, and prices are down more than 20 percent from its 2012 high of $128.40 posted in March.
US crude has recovered from $81.21 touched on Monday, the lowest intraday price since Oct. 6. The contract is about 23 percent below its 2012 high of $110.55, also struck in March.
Two influential Federal Reserve officials said they were prepared to take even more policy action to boost the erratic US economic recovery, and pointed to Europe's worsening debt crisis as the biggest threat to the world's biggest economy.
Across the Atlantic, Germany and European Union officials were urgently exploring ways to rescue Spain's debt-stricken banks. Spain, the euro zone's fourth biggest economy, said it was effectively losing access to credit markets due to prohibitive borrowing costs and appealed to European partners to help revive its banks.
US STOCKPILES
Gains in oil were, however, capped by a smaller-than-expected drawdown in US crude stockpiles last week after 10 straight weeks of stock builds.
US crude inventories fell 111,000 barrels, less than the 500,000-barrel drawdown forecast in a Reuters poll, the Energy Information Administration said. Crude stocks at the US delivery point in Cushing, Oklahoma, rose to a record.