Jon Swartz

USA TODAY

SAN MATEO, Calif. — Popular backup service Dropbox was restored late Friday and -- despite claims from a hacker group claiming responsibility -- said it was an internal issue.

A group called The 1775 Sec said via Twitter it compromised Dropbox's site in honor of Internet activist and computer programmer Aaron Swartz, who committed suicide a year ago.

But Dropbox said the momentary outage arose from routine maintenance.

"Dropbox site is back up! Claims of leaked user information are a hoax," a message on the company's blog said early Saturday. "The outage was caused during internal maintenance."

The outage, roughly around the same time Nieman Marcus said it was the victim of a credit-card hack, created confusion among users and prompted security analysts to warn about security and privacy.

"Businesses and individual users alike need software that protects our information above all else," said Yorgen Edholm, CEO of computer-security firm Accellion. "Without a secure platform, what is the real value of any file sharing solution?"

In November, Dropbox CEO Drew Houston announced that the company had hit 200 million users.