Privacy International also said: "Skype has always proclaimed that it provides a secure method of communication. Hundreds of millions of people have chosen to use Skype, often on the basis of this assurance".
"Many of Skype's users live in troubled areas of the world, where such assurances may carry life or death consequences. Privacy International has a responsibility to ensure that Skype's claims are substantiated."
One of the main concerns includes the failure to provide secure connections, through HTTPS, which allows third parties to tamper with downloads.
The privacy group alleges that China, for example, has been known to produce its own trojan-infected version of Skype, leaving users exposed to interception, impersonation and surveillance. It said given that Facebook, GMail and Twitter offer this level of protection, Skype should also enable such protection.