A day after the Syrian Electronic Army said it had hacked into Skype’s social media accounts, the Internet calling service acknowledged on Thursday it had been hit with a “cyber attack” but said no user information was compromised.

A Tweet posted on Skype’s official Twitter feed on Wednesday read: “Don’t use Microsoft emails (hotmail, outlook), They are monitoring your accounts and selling the data to the governments. More details soon. #SEA”

Similar messages were posted on Skype’s official Facebook pages and on a blog on its website before being taken down later in the afternoon. Skype is owned by Microsoft Corp.

The Syrian Electronic Army, an amorphous hacking collective that supports Syrian President Bashar al-Assad, later claimed the attack.

The SEA also posted on its Twitter feed the contact information of Steve Ballmer, Microsoft’s retiring chief executive, along with the message: “You can thank Microsoft for monitoring your accounts/emails using this details. #SEA”

That message was a reference to revelations last year by former National Security Agency contractor Edward Snowden that Skype, which is owned by Microsoft, was part of the NSA’s program to monitor communications through some of the biggest U.S. Internet companies.

“We recently became aware of a targeted cyber attack that led to access to Skype’s social media properties, but these credentials were quickly reset,” a spokeswoman for Skype said in a statement released on Thursday. “No user information was compromised.”

The NSA’s practices essentially made Microsoft and other technology companies partners in government surveillance efforts against private citizens. The company last month joined seven other top technology firms in pressing President Barack Obama to rein in the US government’s electronic spying.

A US district judge in December ruled the U.S. government’s gathering of Americans’ phone records was likely unlawful and raised “serious doubts” about the value of the so-called metadata counterterrorism program.

A second federal judge ruled later in the month the program was constitutional, raising the possibility the issue would be settled by the US Supreme Court.

Media companies, including The New York Times and the BBC, have repeatedly been targeted by the Syrian Electronic Army and other hacker activist groups that deface websites and take over Twitter accounts.