London-based social music site Last.fm has become the latest website to be hit with a password hack.
The site, which helps users share music recommendations, said that it was investigating the leak of "some" passwords and was asking users to be careful.
The leak follows similar breaches which have hit business social network LinkedIn and eHarmony, a dating website.
More than 6.5m LinkedIn passwords were leaked, causing the site to ask its users to update their details.
Passwords for the sites have leaked and apparently posted online by a user named 'dwdm', who is trying to find help derytping the data.
In a message on its site Last.fm said:
"We are currently investigating the leak of some Last.fm user passwords.
"This follows recent password leaks on other sites, as well as information posted online. As a precautionary measure, we're asking all our users to change their passwords immediately.
"We're sorry for the inconvenience around changing your password; Last.fm takes your privacy very seriously. We'll be posting updates in our forums and via our Twitter account (@lastfm) as we get to the bottom of this."
LinkedIn said it is working with the FBI to investigate the hack of its servers, but did not know of any accounts that had been accessed with the information.
On Thursday it added that it would force affected users to change their passwords.
Security expert Jeremiah Grossman told Reuters that all three websites used Apache software for serving its web pages - but it isn't known if the hacks arise out of a flaw in that program or another method.