McCain, in Mexico, faults Obama on trade

MEXICO CITY (Reuters) - U.S. Republican presidential candidate John McCain took a veiled swipe at Democratic rival Barack Obama over trade on Thursday in the final leg of a Latin American trip aimed at showcasing the Arizona senator's foreign policy credentials.

McCain, who has pledged not to play politics on foreign soil, has nonetheless used his visit to Colombia and Mexico this week to highlight his strong support for free trade and contrast that with the Illinois senator's position.

Obama opposes a trade deal with Colombia and has threatened to pull out of the North American Free Trade Agreement, which groups the United States, Canada and Mexico, if it is not altered to improve labor and environmental provisions.

After a meeting with Mexican President Felipe Calderon, where the two leaders discussed immigration and drug trafficking, McCain criticized Obama, without naming him, for his position on NAFTA.

"I am disappointed at the suggestion that the United States should unilaterally reopen NAFTA," McCain told reporters.

"If there are issues that exist between our countries, whether it be the United States, Canada and Mexico, or other nations with whom we have engaged and ratified solemn treaties, the best way to do that is not in a unilateral fashion."

Obama said during his primary election battle against Democratic rival Hillary Clinton he would he would reopen NAFTA negotiations. But since winning his party's nomination, Obama has backed away from that position.

IMMIGRATION, DRUGS

McCain visited a basilica on Thursday morning and held a lunch with American and Mexican business leaders, where trade featured high on the agenda.

At a news conference in an airplane hanger, McCain touted his positions on immigration and praised an initiative to help stem the flow of illegal drugs into the United States.

"The United States of America and the country of Mexico must secure our borders. That will require some walls, it will require virtual fences," he said in response to a question about whether walls were needed on the U.S.-Mexican border.

He said the United States should create a temporary worker program, which he believed would dissuade people from crossing the border. "When it is known that people who come to our country illegally cannot get a job, that will then cut off the magnet that attracts people."

The U.S. Congress approved $400 million in aid last month to pay for drug smuggling surveillance equipment, the first installment of the $1.4 billion "Merida Initiative" pledged by President George W. Bush when he met Calderon last year.

Mexico welcomed the aid, which will pay for new helicopters and surveillance devices, and said it showed Washington recognized narcotics trafficking is a shared problem.

"I believe that the Merida Initiative may be more important than any agreement that we've made," McCain said.

(Additional reporting by Catherine Bremer, editing by Alan Elsner)