The logo of mobile app 'Snapchat' is displayed on a tablet on January 2, 2014 in Paris. Hackers broke into Snapchat, the hugely popular mobile app, accessing the phone numbers and usernames of 4.6 million users and publishing them online.National Journal

A top Democratic senator said Wednesday that he suspects the photo-sharing app Snapchat is not being forthcoming about a hack earlier this year that exposed personal information of millions of its users.

Senate Commerce Committee Chairman Jay Rockefeller said he had invited Snapchat to testify at a hearing on data breaches but that the company refused to attend.

"When people refuse to testify in front of this committee, my instincts "¦ are they are hiding something," Rockefeller said during the hearing, which featured testimony from a Target executive. "In this instance, on this subject, I think it warrants closer scrutiny."

In January, a hacker published a list of 4.6 million names and phone numbers of Snapchat users.

Mary Ritti, a Snapchat spokeswoman, acknowledged that the company declined Rockefeller's invitation.

"While a representative from Snapchat was not able to testify, we did cooperate fully with the committee and its staff," Ritti said in an email. "We provided information in advance of the hearing and we are committed to continuing that dialogue."

Rockefeller is pushing legislation that empowers the Federal Trade Commission to set data-security regulations and fine companies for violations. At Wednesday's hearing, he urged business groups to negotiate with him on the bill.

"While I'm willing to hear their concerns about my legislation — or any other legislation — I'm not willing to forfeit the basic protections American consumers have a right to count on," he said.

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