A cyberattack "significantly affected" operations and the delivery service of a FedEx courier service Wednesday, the company confirmed.

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" of its TNT Express subsidiary.

TNT Express, which has operations in more than 60 countries and delivers about 1 million documents and packages a day, was acquired by FedEx for about $4.8 billion in 2016.

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

It wasn't immediately clear if the attack is related to a ransomware attack that spread through computers of major companies in North America and Europe in the last two days. The ransomware, called Petya, has reached 65 countries, Microsoft said Wednesday.

FedEx didn't immediately comment on whether the latest attack is related to Petya.

This is the second cyberattack on FedEx within 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