The reason of hack is recent revelations about surveillance programmes being run by US intelligence agencies. the group has also attacked various other media companies, including the BBC, CNN and the Guardian.
The hackers posted on Skype's Twitter account and its blog the following message.
"Don't use Microsoft emails (hotmail, outlook). They are monitoring your accounts and selling the data to the governments,"
The post has since been removed.
Skype has confirmed that it had been hacked but said that "no user information was compromised".
The Syrian Electronic Army (SEA), which says it supports President Bashar al-Assad, has been behind recent hack attacks on the New York Times and Twitter.