Only six EU members — Austria, Belgium, Finland, Germany, Luxembourg and Sweden — are ready to meet the current U.S. deadline of Oct. 26, 2005, according to the EU.

The latest EU request, if granted, would mark the second delay for the e-passport program. Congress already extended the original deadline — October 2004 — last year.

The U.S. imposed the requirement for e-passports embedded with biometric information after the 2001 terrorist attacks in the U.S. It also imposed stricter entry requirements for foreigners entering the U.S.

Once the deadline passes, travelers without an e-passport from formerly visa-exempt countries will have to apply for visas to enter the U.S.

The EU said it is seeking the second delay because "critical aspects of the biometric technology, such as data security and interoperability of reading devices, are still being finalized."

Although Congress is said to be aware of the issue, it is unclear how Washington will respond to the latest EU request.

Separately, the European Commission issued a new study this week on the societal impact of biometric technologies such as fingerprint, iris and face recognition. While supporting the use of biometrics in travel documents, the report outlines a number of specific challenges in developing biometric applications.

The report warns of possible "function creep" and "false expectations" created by biometrics and potential threats to privacy. It calls for clearly defining the purpose of biometric applications, and the need to recognize the technology's limitations.

The report recommends further research and development on technical interoperability, performance and integrity of biometric data along with large-scale field trials.