Critics voiced particular concern that Bern may have been at least tacitly complicit in the secret operation.

Switzerland, which takes pride in its neutral and non-aligned status, “was hosting a quasi ally intelligence agency,” the Tribune de Geneve daily said in an editorial. Swiss officials “very likely” knew what was going on but “closed their eyes” in the name of neutrality, it added.

Home to the United Nations European headquarters and the International Committee of the Red Cross, Switzerland is recognised worldwide for its standing as an honest broker.

But media revelations Tuesday told how for decades the US and West German intelligence services raked in the top-secret communications of governments around the world.

READ: Probe unearths second spying case at Credit Suisse 

The Trojan horse they used was their hidden control of Swiss encryption company Crypto AG.

The company supplied devices for encoded communications to some 120 countries from after World War II to the beginning of this century, including Iran, South American governments, and India and Pakistan.

Unknown to those governments, Crypto was secretly acquired in 1970 by the US Central Intelligence Agency together with the then West Germany's BND Federal Intelligence Service.

Vital intelligence over decades

Together they rigged Crypto's equipment to be able to easily break the codes and read the government's messages, according to reports by the Washington Post, German television ZTE and Swiss state media SRF.

Citing a classified internal CIA history of what was originally called operation “Thesaurus” and later “Rubicon,” the reports said that in the 1980s the harvest from the Crypto machines supplied roughly 40 percent of all the foreign communications US code-breakers processed for intelligence.

The spy agencies were thus able to gather precious information during major crises such as the hostage crisis at the US embassy in Tehran in 1979 the 1982 Falklands War between Argentina and Britain.

They also got information on several political assassinations in Latin America.

The Swiss government said Tuesday it had named a retired federal judge to look into the matter, with his findings due out in June. But Carolina Bohren, a Swiss defence ministry spokeswoman, stressed the difficulties ahead.

“The events in question began in 1945 and are difficult to reconstruct and interpret today,” she said.

Bern also announced it had suspended export licenses for Crypto's successor companies, until the situation has been “clarified”.

But a number of political parties, insisting that far more needed to be done, on Wednesday called for a full-blown investigation.

'Getting out of this mess'

The Swiss Socialist Party wondered in a tweet whether the country's own intelligence service was a “victim or an accomplice”, demanding “clarifications and a full investigation”.

The Greens and Christian Democrats also suggested a parliamentary commission might be called for.

Amnesty International's Swiss chapter meanwhile raised questions about the Swiss authorities' responsibility both for the espionage and for how the information gathered had been used.

“Were our intelligence services and the government aware of the torture and the murders committed by military dictatorships in Chile and Argentina?” it asked in a tweet.

“Did they take any measures? A full investigation must be carried out.”

Switzerland has a centuries-old tradition of neutrality.

It avoided being drawn into either of the World Wars and has stayed outside political and military alliances such as NATO.

Several media reports noted Wednesday that this reputation ended up providing excellent cover for the United States and Germany when they set up their spying operation there.

Whether this was done “out of incompetence, because of a desire to cover for foreign secret service agents, or to profit from the information they uncovered, must now be clarified,” the Tages-Anzeiger daily insisted.

“That is the only way to get out of this mess.”