Swiss data-protection officials have warned against the hasty introduction of civil-rights restrictions as the authorities increase efforts to combat terrorism.
The warning comes after the European Union pledged to implement new counter-terrorism measures in the wake of last week’s bombings in Britain.
Earlier this week EU interior and justice ministers agreed to speed up measures to cut off terrorist funding and boost the sharing of intelligence.
The proposals include a wide range of different exchanges of data, the use of closed-circuit television cameras, storing phone records and introducing passports with biometrical information.
Switzerland, which is not a member of the EU, stepped up surveillance of telecommunications more than three years ago in an effort to fight terrorism.
Under Swiss law Internet Service Providers (ISPs) and telephone operators have to keep a record for six months of all calls made and emails sent by their customers.
Companies also have to store information about the users of pre-paid mobile phones.
The measures have been introduced gradually since the beginning of 2002 and the authorities are planning further restrictions.
The cabinet is due to present proposals later this year on ways to ease restrictions on phone tapping and to extend the storage capacity of telecoms data.
But the federal data-protection commissioner has repeatedly warned against undermining personal privacy and civil liberties.
"You can discuss measures to improve security, but this should not lead to hasty action in the wake of terrorist attacks," said Kosmas Tsiraktsopoulos of the Federal Data Protection Commission.
He said there must be a balance between the right to security and privacy.
"There are already several laws and regulations in place to prosecute people who pose a threat to internal security and prevent terrorist attacks."
Guido Balmer of the Federal Police Office said credible prevention could be achieved by a series of measures, including tapping into databases and acting on information from the intelligence services.
He also welcomed the use of surveillance cameras, but cautioned against high expectations: "It is not the answer to all questions."
For his part, Tsiraktsopoulos is against plans to extend the collection of telecoms data and to allow the bugging of telephones for preventive purposes.
He is also firmly against proposals to install video-surveillance cameras on a large scale in Switzerland.
"Video surveillance cannot prevent terrorist attacks," said Tsiraktsopoulos.
Surveillance of citizens in Switzerland was restricted by the government in the wake of the discovery in 1989 of secret police files on nearly one million people and organisations considered a security risk.
The European telecoms industry has voiced concern about the cost for telecoms firms and ISPs to create huge databases and store the information.
The Swiss Information and Communications Technology Association (Sicta) shares the concern of its European counterpart.
Sicta deputy managing director Josef Erni warned that new generations of communications technology made the management of the increasing amount of data difficult and time-consuming.
"Who is able to have all the specialists at hand to deal with the many languages used?" said Erni.
He added that criminals were in any case likely to use special codes and other technical means to escape tighter controls.
According to Erni, Swiss operators have made significant investments in databases to comply with government regulations.
"The costs of running the systems are covered, but not the initial investment," he said.
swissinfo, Urs Geiser
Jan 2002: Six-month record on all telephone calls and emails becomes mandatory.
December 2002: Parliament rejects plans to introduce special anti-terrorism law.
March 2003: Details of recent mobile-phone customers have to be registered.
July 2004: Bilateral deal with United States to combat terrorism.
October 2004: Details of all pre-paid mobile customers must be registered.
The 2004 report on internal security found that terrorism and extremism continue to pose a threat to Switzerland, but that the country is not a prime target.
The government is due to present draft proposals on easing phone tapping for preventive purposes and extending the collection of telecom data.
The federal data protection commissioner has repeatedly warned against restricting civil liberties, despite the threat of terrorism.