New York, Dec 19 (IANS): Oil prices dived, as mounting anxieties over supply surplus cast a pall over investors across the board.

Oil prices plunged more than 7 percent to the lowest level since August 2017, as global supply continued piling up amid sagging demand due to signs of slowing global growth, Xinhua news agency reported on Wednesday.

Britain's largest oilfield Buzzard has resumed operation following repairs on pipework, according to its operator Nexen. The top UK producing field, pumping around 150,000 barrels per day, provides the lion's share of the country's export via the Forties pipeline.

Worsening the situation, investors confidence is further retreating amid broad sell-off in US stock markets.

An increasing number of investors expected global economic growth to weaken over the next year, marking "the worst outlook on the global economy since October 2008," said an investor survey in December by Bank of America Merrill Lynch.

The survey showed "the biggest ever one-month rotation" into bonds as investors fled stocks amid sharp losses in global equity markets, according to the survey.

Oil output from seven major U.S. shale basins is forecast to record the biggest increase since September of 134,000 barrels per day (bpd), and to hit 8.166 million bpd in January next year, the U.S. Energy Information Administration said in a report on Monday.

Adding to the worrying impact, oil stockpiles at Cushing, Oklahoma, a delivery hub for U.S. crude futures, rose over 1 million barrels between Dec. 11 and Dec. 14, beyond investors' expectation, according to U.S. energy data provider Genscape.

The West Texas Intermediate for January delivery plunged 3.64 U.S. dollars to settle at 46.24 dollars a barrel on the New York Mercantile Exchange, while Brent crude for February delivery slumped 3.35 dollars to close at 56.26 dollars a barrel on the London ICE Futures Exchange.