Republican presidential hopeful John McCain has said U.S. immigration laws should only be reformed after security is tightened on the Mexican border.

Senator McCain was speaking during a visit to Mexico, where he reiterated his support for free trade.
His Democratic rival in November's poll, Barack Obama, has said he would renegotiate NAFTA, the free trade deal between the U.S., Canada and Mexico.
McCain arrived in Mexico after spending two days in Colombia.
Regarding policy, illegal immigration is set to be one of the key issues in the presidential campaign.
McCain was the co-author of a comprehensive reform of U.S. immigration laws that stalled in the U.S. Congress last year.
Speaking in Mexico City, McCain repeated his support for allowing more immigrant workers to enter the U.S.
But he warned that any reform must come after boosting security along the Mexican border.
""We must have comprehensive immigration reform but the American people want our borders secure first,"" he told reporters.
Immigration, drug-trafficking and trade were the focus of his talks with Mexican President Felipe Calderon, after which McCain sought to highlight the differences between himself and Senator Obama on trade.
""If there are issues that exist between our countries, whether it be in the United States, Canada and Mexico, or other nations with whom we have engaged and ratified solemn treats, the best way to do that is not in a unilateral fashion,"" McCain said.
Free trade has become a key issue in the presidential campaign and in the battle for control of Congress, against a backdrop of economic woes and job losses in the U.S.
McCain arrived in Mexico after a two-day visit to Colombia where he urged the U.S. Congress to pass a long-stalled free trade deal with Bogota.
(Source: BBC)