By Pablo Bachelet

WASHINGTON (Reuters) - Immigration opponents Tuesday blasted a popular Mexican ID card as unsafe and threatened legal action against banks and other public institutions that accepted the document as proof of identity.

Immigration opponents charged at a news conference that the card was a backhanded way for Mexico to secure quasi-legal status for the 3 million to 5 million immigrants illegally residing in the United States.

The so-called Matricula Consular, a wallet-sized ID card, is increasingly accepted in the United States by everything from hospitals to banks.

Marti Dinerstein, president of Immigration Matters, a public policy analysis firm in New York and a fellow at the Washington-based Center for Immigration Studies, called the card an "audacious political maneuver" by Mexico.

"Not only does it subvert U.S. immigration law, it is not even a secure identity document," she charged.

She cited the arrest of a man in Denver who had three Matricula Consulares IDs under different names as proof that security can easily be breached.

Although Mexico has been issuing Matriculas Consulares in the United States for more than 100 years, it introduced a tamper-proof version in March 2002 and consular officials launched an aggressive campaign for the card's acceptance.

Mexican officials say they are working to make the Matricula even safer.

"New technology will allow us to establish a database that will connect all the consulates with our capital," said Roberto Rodriguez, the general director for consular services, in a phone interview with Reuters.

The card is accepted by 74 banks to open accounts and by 800 law enforcement agencies, which skip background checks for card holders. And 13 states accept it to issue driver's licenses, according to the Center for Immigration Studies.

Acceptance by banks is crucial because immigrants can save millions by using banks instead of costly wire transfer companies. Banks could also gain a portion of the $9.3 billion that Mexicans sent back to Mexico in 2001.

The card has been at the heart of a growing controversy between Mexican officials and immigration opponents.

Mexico has been pushing for a broad immigration agreement with the United States, but the Bush administration put the issue on the back burner after the Sept. 11 attacks.

While Mexico has the legal right to issue the Matricula, Craig Nelson, director of Friends of Immigration Law Enforcement, wants to make U.S. institutions more accountable for accepting the ID.

Those that accept the ID could be risking lawsuits if the bearer of the card goes on to commit an illegal act, he said.

"Accepting the card would expose either banks or public entities to civil liabilities," he said.

Copyright 2003, Reuters News Service