NEW YORK (REUTERS, AFP) - Wall Street sank at the open on Thursday as doubts regarding the health of the global economy saw investors fleeing to safe haven assets.

The Dow Jones industrial average was down 139.16 points, or 0.87 per cent, at 15,775.58 The S&P 500 was down 15.76 points, or 0.85 per cent, at 1,836.1 and the Nasdaq Composite index was down 63.35 points, or 1.48 per cent, at 4,220.24.

US oil prices continued to fall, opening in New York below US$27 a barrel. Concerns about falling oil prices, related to China's slowing economy and the global slowdown, are roiling markets.

Analysts also cited remarks from Federal Reserve Chair Janet Yellen on Wednesday that highlighted rising worries about the global economy but also kept alive the possibility of additional interest rate increases in 2016.