Attempts by opposition parties in Germany to bring Edward Snowden to Berlin to give evidence about the NSA’s operations have been thwarted by the country’s highest court.

The Green and Left parties wanted the whistleblower to give evidence in person to a parliamentary committee investigating espionage by the US agency, but Germany’s constitutional court ruled against them on Friday.

The government has argued that Snowden’s presence in Germany could impair relations with the US and put it under pressure to extradite him.

It has suggested sending the committee – which consists of eight MPs – to interview him in Moscow, where Snowden is living in exile. Snowden has said through a lawyer that he is prepared to speak to the panel only if permitted to do so in Germany.

Opposition MPs have been vocal about their wish for Snowden to be granted asylum in Germany, where anger towards the NSA and sympathy for the whistleblower has been particularly high.

If Snowden were to be allowed to enter Germany, the clamour for him to be able to stay would be strong and resistance from the government would be likely to be met with civil unrest.

Support for Snowden in Germany reached a peak after allegations came to light that Angela Merkel’s phone was bugged. But Germany’s top public prosecutor announced this week that an investigation had so far failed to find any firm evidence for the claim.

Harald Range, who launched an investigation in June, did not rule out that it could be true, but said: “The document presented in public as proof of an authentic tapping of the mobile is not an authentic surveillance order by the NSA. There is no proof right now that could lead to charges that Chancellor Merkel’s phone connection data was collected or her calls tapped.”

Range said the investigation would continue. He said that neither Snowden, the reporter for Spiegel magazine who was in possession of a document that appeared to be evidence of tapping, nor Germany’s foreign intelligence agency, the BND, had presented him with any other details.

The affair caused considerable tension between Berlin and Washington. German attempts to secure a no-spying agreement with the US were unsuccessful. Washington did not seek to deny the charges and assured Merkel that it would not tap her phone in future.