LONDON (Sept 1): Oil prices fell sharply on Tuesday after official data showed China's manufacturing sector, one of the main engines powering the world's biggest energy consumer, contracted at its fastest pace in three years.

China's official Purchasing Managers' Index (PMI) dropped to 49.7 in August from 50.0 in July, reinforcing concerns over the world's second-largest economy.

The figures helped spur a retreat in oil prices after three days of hefty gains. Investors took profits after Brent and US crude both soared more than 8% on Monday, traders said.

"It was primarily the China fear factor," Carsten Fritsch at Commerzbank in Frankfurt told the Reuters Global Oil Forum.

Benchmark Brent crude dropped $2.53 to a low of $51.62 a barrel. It was trading around $51.90 by 1330 GMT. On Monday, Brent climbed $4.10, or 8.2%, extending a rally from a 6½-year low at just above $42 on Aug 26.

US crude was down $2.10 at $47.10 a barrel. On Monday it settled up $3.98, or 8.8%.

Oil prices rallied from their lowest levels since the global financial crisis in what traders said was a bout of short-covering after more than three months of falls.

Figures from the Energy Information Administration (EIA) on Monday showed US oil output peaked at just above 9.6 million barrels per day (bpd) in April before falling by more than 300,000 bpd over the following two months.

But the global market is still heavily oversupplied.

Oil producers in the Organization of the Petroleum Exporting Countries are pumping over 2 million bpd more than required, forecasters say, filling oil stockpiles worldwide.

A Reuters poll on Tuesday forecast Brent would average $62.30 a barrel in 2016, down $6.70 from projections a month earlier.

Bank of America Merrill Lynch said it was lowering its 2016 and 2017 crude oil projections because balances looked soft and oil production costs were falling:

"Growth concerns around China, coupled with the expectation of increased Iranian output in 2016, have temporarily driven oil prices even lower than we anticipated," Merrill Lynch said.

Investors awaited US data, including oil stocks, manufacturing and vehicle sales, due later on Tuesday.