Oil prices dipped yesterday as concerns over slowing economic growth weighed on markets.

International Brent crude oil futures were at $71.78 per barrel down 5 cents from their last close, while the U.S. West Texas Intermediate (WTI) crude futures were down 4 cents, at $65.87 per barrel.

“Disappointing industrial data out of China along with concerns over emerging market economies centered on Turkey weighed on commodities,” Edward Bell of Emirates NBD bank said in a note on Sunday.

In the United States, U.S. energy companies last week kept the oil rig count unchanged at 869, according to Baker Hughes energy services firm on Friday.

“The recent softening in benchmark prices should temper the pace of growth in U.S. exploration and production activity and lead to slower overall output growth,” Bell said.

Outside the United States, traders said U.S. sanctions against Iran could soon impact prices.

The U.S. government has introduced financial sanctions against Iran which, from November, would also target the country’s petroleum sector.

Iran produced around 3.65 million barrels per day of crude in July, according to a Reuters survey, making it the third biggest producer within the Organization of the Petroleum Exporting Countries (OPEC), behind Saudi Arabia and Iraq.