Passport, please?

German and French media on Friday cited a joint letter from the German and French interior ministers, Hans-Peter Friedrich and Claude Gueant, said to have been sent to the Danish EU presidency on April 17.

The document says that when any Schengen nation fails to meet its obligations to manage the zone's external frontiers then partner nations should have "the possibility, as a last resort, to reintroduce internal frontiers for a period not greater than 30 days."

The zone now spans 26 European countries, including four non-EU members (Switzerland, Norway, Iceland and Lichtenstein), that are collectively home to 400 million residents.

Schengen refers to the Luxembourg town where in 1985 five of the then 10 European Community nations freed up cross-border movements to boost travel and trade.

The expanded treaty requires only controls of travelers crossing the zone's borders with non-member countries but sets few transit checks within the 26 nations. In Germany these are limited, for example, to police spot checks on trains.

Sights apparently set on Greece

The German newspaper Süddeutsche Zeitung said on Friday the ministers fear "illegal immigration" into Europe across the Schengen's southern and eastern frontiers, which could be a reference to Greece - itself a Schengen nation. Economically troubled Greece has become a major hub for irregular immigration into Europe via Turkey and the Middle East.

The news agency AFP said the ministers also insist in their letter that decisions to make short-term closures should not be left to permanent Brussels officials but be the sole preserve of national ministers voting within the European Council of EU members states.

Last month, while campaigning ahead of Sunday's first-round French presidential election, President Nicolas Sarkozy said without "serious progress" on a treaty rewrite France would "suspend its participation."

The German-French proposal will, according to the Süddeutsche Zeitung, be discussed by EU interior ministers at a meeting next Thursday. A Schengen amendment could be reached in June.

Last year, France and Denmark used an existing exception clause in the treaty to briefly patrol parts of their borders. The French border with Italy was subject to passport controls in an effort to stop refugees from northern Africa, and Denmark checked travelers on its borders with Germany and Sweden in a move that drew diplomatic protests.

ipj/sms (AFP, Reuters, dpa)