McALLEN, Texas (AP) _ Hundreds of Mexicans were blocked from crossing the border for failing to secure new high-tech IDs, but federal immigration agents said they were pleased the number wasn't higher.

By late Tuesday, more than 3,500 Mexicans had been turned away for missing Monday's deadline for converting their border-crossing cards into ``laser visas.''

An average of 543,975 people a day cross the 1,962-mile U.S.-Mexican boundary into California, Arizona, New Mexico and Texas and an estimated 2 million of 5.5 million cards still need to be replaced.

``It's been relatively quiet, far beyond our expectations. That's great news for us,'' Immigration and Naturalization Service spokesman Tomas Zuniga said.

Some of those turned away said they didn't know about the deadline, while others thought Congress already had or would grant an extension.

The new visas, which feature fingerprints and data encrypted in magnetic strips, permit Mexicans to enter the United States and travel within 25 miles of the border for up to 72 hours at a time. Congress mandated the use of the new cards in 1996 but has extended the deadline at least twice.

The wait for those who missed the deadline may be long. U.S. consulates in Mexico Monday were scheduling appointments for March.