Hackers have broken into Lady Gaga's website and stolen thousands of personal details, according to the Guardian.
The Swagsec hacker group stole Lady Gaga fans' details on 27 June, including names and email addresses. Financial details were not stolen, Universal Music told the Guardian in a statement.
"All those affected have been advised," Universal Music said.
Security company Sophos said that "perhaps the website was doing a lousy job at securing its fans' information" in a blog post on Monday.
The hackers took a content database dump, with email, first name and last name records compromised, said Sophos.
Lady Gaga's UK website was designed by a Manchester firm called Retrofuzz.
A Retrofuzz employee declined to comment on Tuesday, but said that Universal Music had a team looking into the hack.
Lady Gaga is a recording artist signed to Polydor Records.
Update 19-7-11 Universal Music said UK privacy authority the Information Commissioner's Office had been informed about the hack:
"Various websites hosted by Universal Music UK were targeted by an internet hacker on 27 June.
The hacker took a content database dump from www.ladygaga.co.uk and as a result a section of email, firstname, lastname records were accessed. There were no passwords taken and no financial information taken.
Universal Music takes information protection very seriously and has put in place additional measures to protect personally identifiable information.
All those affected have been advised of the intrusion into our sites. We also informed the Information Commissioner's Office, the police and our trade body, the BPI."