(Bloomberg) -- Regulators have concluded that at least one wireless carrier apparently violated U.S. law by improperly disclosing consumers’ wireless data, the chairman of the Federal Communications Commission said in a letter Friday.

FCC Chairman Ajit Pai didn’t identify any company in the letter to lawmakers, which said the agency will consider levying a punishment that he also didn’t specify.

“I wish to inform you that the FCC’s Enforcement Bureau has completed its extensive investigation and that it has concluded that one or more wireless carriers apparently violated federal law,” Pai said in the letter sent separately to 11 House Democrats.

The lawmakers in November accused the FCC of failing to protect consumers’ privacy, and said that major wireless carriers were disclosing real-time location to data compilers without consumers’ consent or knowledge. The information could be obtained by companies including bounty hunters, the lawmakers said in a letter.

AT&T Inc., T-Mobile US Inc. and other carriers came under public scrutiny after Motherboard reported last year that they sold subscribers’ geolocation data to third-party companies, including Zumigo Inc., which provides location data services. The companies have since told the FCC that they stopped selling subscribers’ data.

Pai in his letter said he intends to seek a vote by fellow commissioners on a possible fine of the companies.

Tina Pelkey, an FCC spokeswoman, declined to elaborate saying the agency would let Pai’s letter speak for itself.

AT&T, T-Mobile US and CTIA, a trade group for wireless carriers, didn’t have immediate comments.

To contact the reporter on this story: Todd Shields in Washington at tshields3@bloomberg.net

To contact the editors responsible for this story: Jon Morgan at jmorgan97@bloomberg.net, Elizabeth Wasserman

©2020 Bloomberg L.P.