The European Union's top justice official has proposed tougher anti-terror measures, including gathering data from airline passengers flying into the 27-nation union.
But EU Justice Commissioner Franco Frattini said to avoid any "security loopholes" in the event of the measures coming into force in 2010, he would like non-EU member Switzerland and other Schengen states to agree to his plan.
Frattini said on Tuesday that Europe "cannot be complacent" against the threat of new attacks after EU anti-terror experts warned earlier this week that more attacks by Islamic extremists were likely.
The most controversial of the Italian's plans – which would have to be approved by EU governments – calls for EU nations to adopt EU-wide airline security measures similar to those used by the United States, storing a long list of passenger data that would be retained for 13 years.
Only those passengers flying into or out of the EU would be affected – those flying inside the EU would not. As Switzerland is not in the EU, passengers flying into and out of Switzerland would have their data collected.
Currently, only three EU states – Britain, Denmark and France – have rules to collect and use Passenger Name Record (PNR) data, but their national systems vary substantially.
When the Swiss voted in September 2006 to join the Schengen area in 2008, they agreed to abandon systematic identity checks on its borders. In return, they would gain access to a Europe-wide electronic database on wanted and missing persons, illegal immigrants and property.
Frattini acknowledged that Switzerland's joining the Schengen area in 2008 would create a "security loop" bang in the middle of Europe, with terrorists being able to fly into Switzerland and then "take a taxi" to anywhere in the Schengen area.
To remedy this, Frattini said he "would like" – and for the EU states to agree – for the measures to be adopted by Switzerland and the other Schengen members.
This in turn would mean that the Swiss authorities would have to collect and process data on non-EU passengers.
Frattini's plan was slammed by data privacy advocates as going too far.
"Retaining passenger data would only make sense if such a system were to be implemented for train passengers and cars as well, but if this were announced publicly now, there would be huge protests," said German Data Protection Commissioner Peter Schaar.
Schaar, who also chairs an EU panel of national data privacy experts, said the EU plan to log 19 pieces of sensitive passenger data such as email addresses, telephone numbers and payment details of flight tickets mirrored the US recording system, which has already been criticised for violating the privacy rights of Europeans.
The plan would see airlines forced to hand over PNR data to national policing authorities before the scheduled flights, who would assess the potential risk of those flying into the 27-nation bloc or leaving it.
The data "passenger profile", which will include how the flight ticket was purchased, where, when and by whom, will be initially retained for five years. It will then be kept on file, but left in a "dormant" database for a further eight years before it is permanently deleted.
Authorities from member states can use the data to question and even deny entry to people whom they deem a terror risk, Frattini said.
The Swiss justice ministry did not want to comment on Tuesday, saying it would first have to examine whether such a system would make sense for Switzerland.
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Stricter US border checks came into force in October 2005 and apply to citizens from 27 countries, including Switzerland. The US accord with Switzerland runs until autumn 2008.
The checks are partly designed to deter terrorists from taking advantage of easier entry restrictions in place for some countries.
They involve the collection and storage of biometric data such as fingerprints and digital photographs.
Incoming airlines are also asked to hand over information such as passengers' religion and credit card numbers – a move which has been criticised by the Swiss.
Switzerland is not a member of the European Union.
The federal government describes EU membership as a "long-term option".
Switzerland is linked to the EU via a series of bilateral accords.
The EU is Switzerland's main trading partner.
In the 1990s debate over Switzerland's policy towards Europe polarised the national political landscape.
The 1985 Schengen Treaty aimed to create an area where individuals could travel freely from country to country, and was signed by five EU members: Belgium, Germany, France, Luxembourg and the Netherlands. It was subsequently adopted by most other member states.
Although most Schengen countries require citizens to carry identity cards, the removal of frontier controls on most internal EU borders has made it much easier for criminals to travel undetected into different legal jurisdictions - and to evade prosecution. This has led to significant efforts to develop co-operation between prosecutors and investigators, notably in the field of extradition.