U.S. Homeland Security Secretary Tom Ridge and Mexican Interior Secretary Santiago Creel said officials on both sides of the border have redoubled their security efforts without interrupting the steady flow of commerce that is so important to the strong trade partners.

Ridge also said that a plan by U.S. President George W. Bush to grant temporary residency to millions of Mexicans with U.S. job offers would help make the border safer by encouraging legal migration.

Ridge and Creel were among top-level officials from the United States and Mexico who gathered Tuesday in Mexico City to review a range of issues including border security and migration.

No terrorists are believed to have crossed into the United States from Mexico, but the U.S. and Mexican security chiefs underscored the importance of not letting down their guard against potential threats.

Ridge said U.S. intelligence agencies have received reports that the border "is a means by which the terrorists have considered infiltrating" the country.

"The traditional openness of our border is potentially a very attractive way of delivering terrorists or weapons into the United States," he said.

Using its army, navy and national police, Mexico has redoubled efforts to "safeguard the country and its interests from any terrorist attack or prevent our territory from serving as a passage toward other countries, principally the United States," Creel said.

Strengthening crime-fighting efforts against drug traffickers and other organized criminals in Mexico is another important way to keep the border safe, Ridge said.

"Drugs are a weapon of mass destruction," he said, adding that he believed drug traffickers wouldn't hesitate to cooperate with terrorists.

Both Creel and Ridge said they had been successful in tightening security measures without significantly interrupting the steady flow of commerce between the two countries, by designating specific traffic lanes at the ports of entry to cargo vehicles.

Ridge said some congressional members and senators have differing opinions on Bush's migration accord, but that the president is willing to take up the issue with the new Congress in 2005.

The meetings Tuesday also touched on some sensitive issues in Mexico regarding the border and security.

The posting in January of U.S. agents at the Mexico City airport sparked outrage among Mexicans as has the use of pepperball guns by the U.S. Border Patrol when dealing with aggressive migrants along the border.

Ridge explained Tuesday that the pepper-balls are used in "very selective circumstances" with prior training and monitoring, noting that Border Patrol agents frequently risk their lives to aid migrants.

Creel said each country has the sovereignty to protect its borders with a caveat.

"We have emphasized to the American government that the actions that are carried out against the migrants should always respect their human rights, their dignity." Using formal financial institutions to send billions of dollars in remittances from Mexican migrants in the United States to relatives back home is another important way of warding off criminal enterprises such as money laundering, officials said Tuesday.

World Bank representatives participating in the binational meetings said Mexico and the United States have become a model for other countries by using these transfer methods to send remittances, which totaled US12.4 billion through the first nine months of the year and a record a record US13.3 billion last year.

"When the transfers are made through banking systems, it is much more difficult to violate the security and integrity of the remittances," said Alonso García Tames, deputy secretary of Mexico's Treasury Department.

According to the Bank of Mexico, 85 percent of money transfers from the United States to Mexico were sent via formal banking institutions in 2003, which officials said was a dramatic increase over previous years.

Last year, remittances surpassed foreign investment to become the country's second-most important source of revenues after oil.

Mexican officials say there are about 25 million people of Mexican origin living in the United States.

U.S. Education Secretary Rod Paige, on his third visit to Mexico as secretary, said that countries around the world have expressed concern that new security measures may be reducing access to U.S. universities.

"Our nation is an open society and we've had to learn to get the proper balance of being an open society and being a secure society," Paige said. "We've asked other nations to understand this and to exercise some patience here."