Mexico's foreign affairs secretary says the government will not tolerate human trafficking and provided new details of the weekend "rescue" of nearly 800 migrants packed into semi-trailers.

Marcelo Ebrard says more than 150 of those migrants were children and says he considers it a rescue because the people were stuffed into the trucks and could have suffocated.

Ebrard said Monday that each of the migrants had paid $3,500 in their countries of origin to be smuggled to the United States. Some who paid $5,000 were entitled to a second attempt if the first failed.

He says their payments were made in their home countries or in the U.S., but as they passed through Mexico they also were going to pay "commissions" to ensure their free passage.