In the build-up to a bilateral meeting between U.S. and Mexican officials, Mexican President Vincente Fox is stressing the importance of reaching a migration agreement between the two countries. The two-day meeting begins Tuesday in Mexico City.

The U.S. delegation is being led by Secretary of State Colin Powell. One of the principal themes the U.S. side wants to make progress on is increased security along the more than three thousand kilometer border that divides the U.S. and Mexico.

The major goal of the Mexican side is to give legal status to millions of Mexicans who live and work in the United States. Many are still undocumented.

A migration deal between the two countries was high on the agenda of the Bush administration but was sidetracked by the attacks of September 11, 2001. And, when Mexico refused to support the United States in the war against Iraq, it lost yet more priority status.

Nevertheless, a migration agreement remains the main strand of President Fox's foreign policy. In an interview Monday, the president called an agreement vitally important to Mexico's people, but he also said he understood the need for border security.

"People must have the liberty to move to any other country looking for their own prosperity and opportunities for progress. But we understand that we have to move according to the relationships we have among countries, specifically in relation to security and terrorism. We understand that. We are very careful with our borders, and work joint programs with Europe, Spain, Switzerland, with the United States and Canada in trying to collaborate against terrorism.

Now that President George Bush has been re-elected for another four year term, the Fox administration, which only has two more years until its course is run, is pressing for the U.S. Congress approve a migration agreement.

Each year, more than three hundred Mexicans and other undocumented migrants mostly from Central and South America, die attempting to illegally cross the border into the United States.

The Mexican economy depends on the billions of dollars migrants living in the United States send home. The sum is now more than earnings from Mexican tourism, and is only second in cash terms to what Mexico gets from its oil fields.