Oil firmed above $61 on Friday as fundamental support came from consumer nations such as China, the United States and Africa's top producer Nigeria after weeks of equity-led rallies.

U.S. crude futures were up 71 cents at $61.76 a barrel by 4:18 a.m. EDT. It hit a six-month high of $62.26 this week.

London Brent was trading 75 cents higher at $60.68.

Oil has recovered from a five-year low below $33 in December, having plunged from record highs above $147 last July.

U.S. investment bank Goldman Sachs said the hike in prices this week was due to real oil market fundamentals and not just hedging against a weak dollar and equity market rallies.

The oil market was shocked by disruptions in Nigeria, refinery problems in the U.S. and a strong gasoline market, Goldman said in a research note.

The Nigerian military has launched its biggest campaign for years in the country's oil heartland, bombarding militant camps, which has sent shockwaves and fears of further supply disruptions from the West African country through oil markets.

Goldman said recent refinery fire and outages in the world's top consumer, the United States, had also unnerved markets.

The refinery problems pushed up gasoline prices ahead of the Memorial Day holiday this weekend, which kicks off the traditional U.S. driving season until July.

Support also came from China, the world's second-largest energy consumer. Data on Friday showed China's apparent oil demand rose by 3.9 percent in April from a year earlier, its first significant rise since October last year.

Oil traders are expected to shift their focus to next week when the Organization of the Petroleum Exporting Countries will meet to review its output policy on Thursday.

OPEC is broadly expected to keep its official production levels unchanged as rising prices have eased pressure on budgets and there are hints of economic recovery over the next year, a Reuters poll showed on Thursday.

(Additional reporting by Jennifer Tan in Singapore; editing by James Jukwey)