Canadian citizens are exempt from a U.S. plan to tighten border security through increased screening of foreign visitors, Homeland Security Secretary Tom Ridge (search) said Friday.

Ridge and Canadian Deputy Prime Minister John Manley (search) emphasized the U.S. policy to exempt Canadian citizens from the Visitor Immigrant Status Indication Technology (search), or the VISIT system, approved by Congress could change as implementation plans solidify.

The plan is intended to increase security along what is known as the world's longest undefended border without obstructing commerce and traffic that fuels a trade relationship worth more than $1 billion a day, according to U.S. and Canadian trade figures.

The VISIT system is scheduled to take effect at airports and seaports starting next year, and at land border crossings at the start of 2005.

Manley has expressed concern the system would jam the land border crossed by 200 million people each year by requiring Canadian citizens who now simply show their passports to fill out forms or undergo time-consuming screening for entry-exit records.

Most of those who drive across the border are Canadian and U.S. citizens, and a joint statement issued by Manley and Ridge said citizens of both countries "would not be subject to the U.S. VISIT program under current U.S. policy."

Ridge stressed that U.S. policy regarding the border with Canada must be practical, taking into account the important economic and social ties they share.

"The integrated natures of our economies, communities and families suggest to me the argument of practicality will prevail," he said.

Ridge and Manley announced an expansion of the NEXUS and FAST programs that create special lanes for low-risk goods and people to cross land border points, along with an agreement in principle to cooperate in developing science and technology to enhance border security.

Canada became a security concern to the United States in December 1999, when an Algerian living illegally in Canada was caught trying to enter Washington state with explosives in the trunk of his car. The man, Ahmed Ressam, has been convicted of plotting to bomb Los Angeles International Airport during millennium celebrations.