DENVER -- Several large airports, including Denver International, have proposed changes in a federal law that they say impedes efforts to fingerprint all employees as part of a background check.

The law, which went into effect in January, requires employees hired after Dec. 23, 2000 to be fingerprinted if they have access to secure areas. It does not address those who were on the job before that, hampering airports' efforts to recertify employees as a security precaution after the Sept. 11 terrorist attacks.

Checking employees' fingerprints against an FBI database could help prevent hiring criminals, officials of several airports said.

Officials at Miami International Airport and Boston's Logan International Airport have asked for specific authority to fingerprint all employees as part of suggestions sent to a task force on airport security formed Sept. 16 by Transportation Secretary Norman Mineta.

"We think enhanced background checks for all airport employees is critical," said Logan spokeswoman Barbara Platt. "In addition to the standard criminal background checks, we'd like to see the names of all personnel cross-checked with the FBI's watch list as an additional measure."

Denver airport officials have asked the Federal Aviation Administration and members of Colorado's congressional delegation to look into the law.

"That would be just one more thing I think that might give the traveling public a certain level of confidence that we're going above and beyond, trying to create as safe an environment as possible," Denver International Airport spokesman Steve Snyder said.

FAA spokesman Paul Takemoto said from Washington that employees hired before Dec. 23 could be fingerprinted as part of a background check only if certain criteria were met.

Those conditions are: if a job applicant cannot account for a period of unemployment of one year or more during the previous 10 years; if the applicant is unable to support statements made in the application form; if there are significant inconsistencies on the form; or if airport officials suspect during the background check that the applicant had been convicted of certain crimes.

The task force report, released Friday, does not specifically mention fingerprinting, but it recommends integrating law enforcement and U.S. intelligence data with airline and airport security systems, including employee background checks.

Under the Airport Security Improvement Act of 2000, all airport employees with access to secure areas hired after Dec. 23, must be fingerprinted as part of their criminal background checks. Employees hired before that date were exempt from the requirement, but the law requires that all airport employees with secure-area access be fingerprinted by the end of 2003.

At Denver's airport, officials have completed the recertification process for about three-quarters of the 23,000 people with security badges. Nobody's security clearance has been revoked, but about 17,500 employees will not be fingerprinted because they were hired before Dec. 23, Snyder said.

"If it's something that new employees have to go through, why isn't it important for existing employees as well?" Snyder said.