WASHINGTON (REUTERS) - U.S. stocks opened lower on Monday, starting February on a dour note as weak economic data out of China exacerbated concerns about a global slowdown and oil prices resumed their downward spiral.

The data from China showed that the world's second-largest economy's manufacturing sector contracted in January at the fastest pace since 2012.

Oil prices fell after the China data added to worries about demand and an OPEC source played down talk of an emergency meeting to stem the decline. Oil prices have fallen more than 70 per cent since mid-2014.

Slammed by collapsing oil prices that have fed doubts about the health of the global economy, stocks have had a volatile start to the year with traders expecting the Fed to scale back the number of rate hikes this year. Coming off the worst January since 2009, the S&P 500 is already down 5 per cent for the year.

"Further weakness in China offers little evidence that their efforts to stabilize economic growth have been sufficiently effective and that would make a worry for commodity prices,"said Mark Luschini, chief investment strategist at Janney Montgomery Scott in Philadelphia.

A 19-commodity Thomson Reuters/Core Commodity CRB Index , was down 1.5 per cent. The index had hit a 13-year low in late January.

At 9:37 a.m. ET (1039 pm Singapore time) the Dow Jones industrial average was down 127.31 points, or 0.77 per cent, at 16,338.99, the S&P 500 was down 14.58 points, or 0.75 per cent, at 1,925.66 and the Nasdaq Composite index was down 33.58 points, or 0.73 per cent, at 4,580.38.

Nine of the 10 major S&P sectors were lower, with the energy index's 2.2 per cent fall leading the decliners. Oil majors Exxon and Chevron were down about 2 per cent.

Wall Street surged over 2 per cent on Friday after the Bank of Japan unexpectedly cut interest rates and technology shares rallied.

A slew of U.S. economic reports is scheduled to be released on Monday, including manufacturing and construction spending numbers.

The reports follow a weak reading of the GDP, which showed that the U.S. economy expanded at an anemic rate in the fourth quarter.

Data on Monday showed U.S. consumer spending was unchanged in December as households cut back on purchases of automobiles and unseasonably mild weather weighed on demand for utilities, but a jump in savings to a three-year high suggested there is enough muscle to boost consumption in the months ahead.