Air Transport Services Group Inc. said Wednesday it has expanded an air cargo delivery pact widely believed to be with Amazon.com Inc., and wants to extend the trial beyond its planned expiration in March.

The freight airline started domestic flights with two aircraft for Amazon in September, part of the online retail giant’s effort to take more control of its shipping operation, and the service was boosted to five Boeing Co. 767s in November.

An executive at the Wilmington, Ohio-based company, asked if ATSG could expand its flights to Europe and China for its “U.S. e-commerce customer,” said it could “if there is a desire for that.”

The company said later Wednesday that any expansion of activity related to e-commerce overseas was unrelated to its trial service in the U.S.

Amazon has also held discussions with air-cargo companies to lease airplanes and establish its own freight operation, with the goal of reducing its reliance on traditional carriers, according to people familiar with the matter.