By P.J. Huffstutter, Karl Plume 

CHICAGO, Aug 25 (Reuters) - The U.S. Agriculture Department retracted weekly commodities export data it had released earlier on Thursday after a technical misstep left traders scrambling and caused uncertainty in the futures markets.

The government said in a statement a new system to publish the weekly export sales report had encountered “challenges that affected the physical dissemination of the export sales data as well as data quality.”

The retraction came after commodities markets closed for the day, and hours after the initial release that traders had immediately questioned.

The export sales report, which has a week-long delay, is a key indicator for traders, input suppliers and farmers as it highlights recent demand for crops such as corn, soybeans and wheat at a time of tight global supplies. It calculates the sales of U.S. commodity goods to international customers such as China and Mexico.

The data was set to be released at 8:30 a.m. EDT (1230 GMT) via USDA’s Foreign Agricultural Service (FAS) website. But on Thursday morning, the report for the week ending Aug. 18 was not online. Instead, the site had a message about the agency launching a new “Export Sales Reporting Maintenance System,” and several broken Web links.

“When I saw there was a troubled rollout, I kind of discounted anything that came out,” said Craig Turner, a grain broker with StoneX. “How much can we trust it with the issues that we had?”

For example, the USDA reported sales of soybeans from the upcoming harvest nearly four times larger than the highest pre-report analyst estimate, and net upland cotton sales totaled 1.9 million bales, up from 49,800 bales the prior week.

USDA prefaced the e-mailed report with a disclaimer saying, “There could be some anomalies in the data related to the transition” to the new system.

Some analysts apologized for sending faulty data to clients. ( Reporting by Karl Plume and P.J. Huffstutter in Chicago Additional reporting by Tom Polansek in Chicago, Mark Weinraub in Chicago and Seher Dareen in Bengaluru Editing by Leslie Adler and Matthew Lewis)