By Drew FitzGerald

AT&T Inc. denied a claim by a hacker group claiming to sell data from more than 70 million of its customers, suggesting that the purported leak wasn't credible.

"Based on our investigation today, information that appeared in an internet chat room does not appear to have come from our systems," the cellphone carrier said in an emailed statement Thursday.

The denial comes after an attacker illegally accessed data of more than 40 million past, current and prospective users of AT&T rival T-Mobile US Inc., a breach that the company is still probing.

The hacked T-Mobile databases included names, birth dates and social-security numbers, among other records. Some stolen T-Mobile user information was offered for sale through an online forum earlier this week.

A different forum post on Thursday offered to sell AT&T records for up to $1 million, posting samples of personal information as proof. The carrier's denial suggests those entries were inauthentic or were gathered from other sources.

Write to Drew FitzGerald at andrew.fitzgerald@wsj.com

(END) Dow Jones Newswires

08-19-21 2323ET