The claim is that Law enforcement and intelligence agencies are today able to access the communications exchanged by Skype users and Microsoft has still not been adequately answered to various question on the matter. Microsoft assumed in good faith sustaining that the access to all messages sent via the chat is performed to remove spam and phishing links. An independent researcher, including security consultant Ashkan Soltani who was hired by Ars Technica, conducted analysis of the case and confirmed that Microsoft access to some of URLs included in chat messages.
Source: https://thehackernews.com/2013/05/does-microsoft-spy-on-skype_4507.html