Human rights campaigners have accused the Swiss government of not doing enough to bring suspected war criminals to justice.
The group, “Trial”, says the government has let suspects slip through its fingers, including Saddam Hussein's half-brother, Barzan al-Tikriti, who was captured on Thursday.
Trial says the authorities often turn a blind eye to the perpetrators of genocide, torture and crimes against humanity.
The group was launched last June and is made up of activists, victims and lawyers - including Geneva's former public prosecutor and tenacious crime fighter, Bernard Bertossa - who would like to see the government do more to track and arrest alleged criminals on Swiss soil.
"We've had a few cases involving war criminals, who have come to Switzerland, stayed for a few months and then were allowed to leave or were expelled," Trial's president, Philippe Grant, told swissinfo.
"We have to remind the authorities that they cannot just sit idly by and watch these people come and go."
Crime and punishment
Grant cites the case of Saddam Hussein's half-brother, Barzan al-Tikriti, as an example of Switzerland's failure to bring an alleged criminal to justice.
He was captured in Baghdad by United States forces on Thursday, but Trial says the Swiss could have nabbed him long ago.
According to Grant, al-Tikriti, a former United Nations ambassador, was permitted to stay in Switzerland for several months after leaving the UN.
This was despite the fact that a judicial complaint had been filed against him for his alleged role in the disappearance of thousands of Kurds during the 1980s.
"The complaint was filed while al-Tikriti was on Swiss territory, but the authorities let him come and go for months before banning him from Switzerland," said Grant.
"They could have arrested him but they didn't, and we think this is quite shocking."
In response to the group's claims, Folco Galli, a spokesman for the Swiss justice ministry, said that Switzerland was doing all it could to help bring international criminals to justice within the framework of existing judicial systems.
"We have been collaborating for years with the UN tribunals for the former Yugoslavia and Rwanda," he said. "We have also supported and ratified the Rome Statute of the International Criminal Court."
One Swiss official, speaking on condition of anonymity, admitted that diplomatic immunity often got in the way of arresting known criminals travelling in Switzerland.
"If an official comes from Sierre Leone on a diplomatic visit we can't touch him, even if we know he's a war criminal," the official told swissinfo.
"If he or she comes to Switzerland as a private citizen, without immunity, then we will investigate and most likely arrest them."
Nicolas Giannakopoulos, an organised-crime expert in Switzerland, agrees that diplomatic immunity is an obstacle to the capture and arrest of what he describes as "dodgy diplomats".
He also believes that governments should take a tougher stance in banning questionable officials from entering the country in the first place.
Giannakopoulos cited the Swiss government's recent decision to rule out asylum for Saddam and his family as an example of what can be done to deter international criminals from entering Switzerland.
"Diplomatic immunity is a problem for all countries, not just Switzerland," he told swissinfo. "But the leaders of this country have taken a political decision in telling the president of Iraq that he cannot come to Switzerland, and this is the only solution."
Grant concedes that Switzerland has taken action in several cases involving international criminals, including the first prosecution of a Rwandan genocide perpetrator outside of Africa. That case resulted in a 14-year sentence.
But he insists this is not enough, arguing that the authorities - at both the federal and cantonal levels - are simply not aware of what the law allows and how it works.
In an effort to raise awareness, the group has published a new guide entitled, "The Fight against Impunity under Swiss Law".
Co-written by Bertossa and Grant, with contributions from a handful of other Trial lawyers, the publication defines various criminal acts and how Swiss legislation applies to them.
It is also aimed at the growing network of non-governmental organisations and victims associations that are working to monitor the movements of alleged abusers.
"These groups are gathering proof and following the comings and goings of these people... and now they can warn us when a bad guy is coming to a conference at the UN, for example," Grant told swissinfo.
"Once we've checked that the information is correct and that the case is solid, we wait for the person to arrive in Switzerland and then we file a complaint... but after that, it's up to the police to step in."
swissinfo, Anna Nelson in Geneva
The Swiss association known as "Trial," has called on the government to do more to capture and arrest international criminals in Switzerland.
The group is made up of human rights activists, torture victims and lawyers, including Geneva's former public prosecutor, Bernard Bertossa.
They have accused the government of allowing human rights violators to go unpunished in Switzerland.
The government says it's doing all it can within the law to pursue and punish the perpetrators of genocide, torture and war crimes.