Konstantin von Notz, chairman of the Green Party contingent on the German parliament's NSA investigation committee, said the government is "breaking minority parties' rights in order to avoid misfortune."
Martina Renner of Die Linke said that the federal government is "scared of his (Snowden's) testimony," Germany's Berliner Zeitung reported.
The Bundestag's NSA investigation committee was set up in March 2014 in the light of disclosures by former CIA employee and NSA security contractor Edward Snowden about mass surveillance practices carried out by US authorities around the globe.
In May 2014 the committee decided in principle to call Snowden as a witness during the course of the investigation. Snowden, who was granted a three-year Russian residency permit in August 2014, could also be called via video link from Russia.
In November the Federal Court of Justice ruled that the German government should provide the conditions for Snowden to be questioned in Germany by the committee, such as a guarantee not to extradite him to the US. However, the CDU, CSU and SDP coalition government has decided to appeal the court's ruling, rather than provide such a guarantee.
The chairman of the NSA investigation committee, CDU representative Patrick Sensburg, said that if the Federal Court of Justice rules in favor of the government's appeal, the committee will take the case to Germany's Federal Constitutional Court on the basis that such a decision would infringe the rights of freely elected MP's conducting the enquiry.