Courier service giant FedEx confirmed Wednesday operations and the delivery service of a subsidiary was "significantly affected" by a cyberattack.

FedEx shares were up about 0.9% Wednesday morning before trading was halted. Trading resumed in the afternoon after the Memphis-based company confirmed the infiltration of "an information system virus."

The attack hit the computer systems of its TNT Express subsidiary, which is a regional courier service provider, FedEx said in a statement.

No data breach "is known to have occurred," it said.

TNT Express' services, including inter-continental delivery, are delayed. The company is offering its other express delivery services as alternatives.

"Remediation steps and contingency plans are being implemented as quickly as possible," it said.

The extent of the financial damage can't be measured at this time, but "it could be material," it said, adding no other FedEx operations had been affected.

This is the second cyberattack on FedEx in two months. In May, FedEx was one of numerous companies around the world that were hit by a worldwide ransomware campaign.

In the May attack, computers in thousands of places in up to 74 countries reportedly had been locked by a program that demanded payment in an online currency called Bitcoin.

FedEx later said the incident disrupted package sorting at the FedEx Express world hub at Memphis International Airport.

Contributing: Wayne Risher of The Commercial Appeal of Memphis