Stocks turned lower by mid-afternoon Tuesday as crude oil struggled to hold above $28 a barrel. 

The S&P 500 was down 0.51%, the Dow Jones Industrial Average slid 0.34%, and the Nasdaq fell 0.93%.

Crude oil prices fell after the International Energy Agency warned commodities could fall even further this year as the market faces "enormous strain." In its first monthly report of the year, the energy watchdog said new supplies from countries such as Iran will leave the oil market with a surplus of 1.5 million barrels a day over the first half of the year.

The Iranian government ordered oil companies to ramp up production on Monday after sanctions were lifted over the weekend. Iran could add 500,000 barrels a day to its output, a significant increase from its current production of around 2.9 million barrels a day.

West Texas Intermediate crude oil was down 3.4% to $28.41 a barrel, hovering at 12-year lows. Oil prices have tumbled 23% so far this year.

Stocks closed out last week at their lowest levels since August amid a renewed selloff in crude oil prices, fresh fears over China and a smattering of poor economic data out from the U.S. The S&P 500 has dropped more than 7% since the beginning of the year.

Global markets closed sharply higher after Chinese economic growth fell as expected. Economic data from the world's second-largest economy frequently has disappointed economists, triggering fears over the intensity of the region's slowdown.

China's economic growth fell to 6.8% in the fourth quarter as trade and consumer spending weakened. The pace was its slowest in six years and pulled 2015 growth down to 6.9%, its weakest level in a quarter-century. However, the measure was as economists had expected and backed up hopes of further stimulus from Chinese officials.

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