Brent crude oil rose for a fourth session on Thursday to above $102 a barrel as investor conviction strengthened that monetary stimulus measures from major central banks would stay in place for the time being.

Brent crude for August delivery was up 62 cents at $102.28 a barrel by 1323 GMT, after settling 40 cents higher at $101.66 a barrel in the previous session. It was on track for its longest stretch of daily gains since mid-March.

U.S. crude was up 50 cents at $96.00 a barrel.

U.S. GDP data on Wednesday that slashed the estimate of first-quarter economic growth assured investors that the Federal Reserve would be in no hurry to scale back its massive bond-buying programme.

Also reassuring the market, European Central Bank President Mario Draghi highlighted downside risks to euro zone growth and said monetary policy would stay accommodative.

"Investors are convinced that there is still plenty of shelf life for the policy of pumping money into the economy," said Michael Hewson, analyst at CMC markets.

Also supportive of oil prices was violence in the Middle East, with Libya the latest focus of attention.

Five people were killed and nearly 100 wounded in clashes between rival armed militias in Libya's capital on Wednesday, Health Minister Nurideen Doghman said.

North Sea supply problems also underpinned prices.

Output at Britain's Buzzard oilfield is expected to stay around 170,000 barrels per day (bpd) for around five days, an industry source said on Thursday, reducing the supply of crude that helps set the Brent benchmark.

Gains in oil were capped by strong global stockpiles.

U.S. gasoline stocks surged 3.65 million barrels in the week ended June 21, in the summer driving season, data from the U.S. Energy Information Administration showed on Wednesday. Analysts had expected a more modest build of 900,000 barrels.

Brent is down more than 7 percent for the quarter so far, on track for a third straight quarterly loss after falling last week on concerns about an economic slowdown in China and comments by Fed Chairman Ben Bernanke that signalled the bank might ease off bond buying.

This would amount to the longest stretch of quarterly losses since late 1997 into 1998.

Brent crude oil prices are forecast to decline further this year and next, pressured by a potential slowdown in Chinese oil demand growth and swelling supplies, a Reuters poll showed on Thursday.

Investors, meanwhile, turned their attention to U.S. non-farm payrolls data due next week to gain further clarity on the economy and prospects for monetary policy.

"This is the more definitive number for the Federal Reserve, because we know that they are comfortable with inflation levels, but unemployment is still not where they want it to be," said Lee Chen Hoay, investment analyst at Phillip Futures in Singapore.