Attempts to introduce a biometric passport in Germany have been thwarted by people smiling, the Financial Times reported today.

Germany started issuing biometric 'ePass' passports a week ago but has had to issue guidelines warning that people "must have a neutral facial expression and look straight at the camera". Visible teeth are apparently also a problem.

Rainner Rinner, who is in charge of the Tiergarten passport office in Berlin, said: "We sent someone home because their picture did not fit with the biometrics."

Germany is the third EU country to begin offering biometric passports, following Belgium and Sweden. Germans have to pay £40 for a new passport compared to £16 for the old version.

The use of biometrics has its fair share of high-profile critics. Peter Schaar, the German government's independent data processing advisor, said: "I am worried that the alleged security gains from the ePass are really an illusion.

"Most of the 9/11 terrorists travelled with legal, not falsified, documents so would not have been caught if the new passports existed."

Schaar is also critical on data protection grounds. "There are no international rules that stop, for instance, Iran or North Korea storing this information. This is a big data protection concern," he said. 

But the German government is adamant that existing passports are a weak link in state security. In 2002 a spot check of 7,700 travellers revealed that 690 passports that were partially or fully falsified.