WASHINGTON – The U.S. trade deficit widened for the first time in four months in December on higher oil imports, the Commerce Department said Friday, but exports continued their upward trend and were nearing record levels.

The nation’s trade deficit expanded 5.9 percent in the final month of 2010, to $40.6 billion from $38.3 billion in November, the government’s data showed.

This marked the first increase and the largest trade gap since September, as the U.S. petroleum deficit hit its highest level since October 2008.

Excluding petroleum, however, the deficit improved.

Joel Naroff, president of Naroff Economic Advisors, said the data show higher gas prices are not just an inflation threat but can constrain economic growth.