Authorities in southern Mexico have sent about 100 more migrants to a detention center amid the government's push to deter Central Americans and others from crossing the country to reach the United States.

Civil rights activist Luis Arbey Perez Cruz in the municipality of Arriaga said the group of migrants was transported to a center near the border with Guatemala on Sunday. He says that "it was five immigration vans, returning to the border."

Pressured by the U.S., Mexico has deployed some 6,000 agents of the new militarized National Guard policing force along its southern and northern borders this month to help deter migrants. In Ciudad Juarez, just south of El Paso, Texas, National Guardsmen turned back migrants trying to cross the border during the weekend.

Bags belonging to migrants without legal permission to be in Mexico sit on the street next to an immigration van parked outside an Attorney General before migrants sitting inside the van are transported to Tapachula from Arriaga, Mexico, Sunday, June 23, 2019. Mexico has completed its deployment of 6,000 National Guard agents to help control the flow of migrants headed toward the U.S. and filled immigration agency posts to regulate border crossings, the government said Friday. (AP PhotoOliver de Ros)

Bags belonging to migrants without legal permission to be in Mexico sit on the street next to an immigration van parked outside an Attorney General before migrants sitting inside the van are transported to Tapachula from Arriaga, Mexico, Sunday, June 23, 2019. Mexico has completed its deployment of 6,000 National Guard agents to help control the flow of migrants headed toward the U.S. and filled immigration agency posts to regulate border crossings, the government said Friday. (AP PhotoOliver de Ros)

A youth without legal permission to be in Mexico sits inside an immigration van outside an office of the Attorney General as he and other migrants wait to be transported to Tapachula from Arriaga, Mexico, Sunday, June 23, 2019. Mexico has completed its deployment of 6,000 National Guard agents to help control the flow of migrants headed toward the U.S. and filled immigration agency posts to regulate border crossings, the government said Friday. (AP PhotoOliver de Ros)wld

A youth without legal permission to be in Mexico sits inside an immigration van outside an office of the Attorney General as he and other migrants wait to be transported to Tapachula from Arriaga, Mexico, Sunday, June 23, 2019. Mexico has completed its deployment of 6,000 National Guard agents to help control the flow of migrants headed toward the U.S. and filled immigration agency posts to regulate border crossings, the government said Friday. (AP PhotoOliver de Ros)wld

People without legal permission to be in Mexico leave an office of the Attorney General before being sent to Tapachula in an immigration van, as a member of the National Guard, left, stands watch in Arriaga, Mexico, Sunday, June 23, 2019. Mexico has completed its deployment of 6,000 National Guard agents to help control the flow of migrants headed toward the U.S. and filled  immigration agency posts to regulate border crossings, the government said Friday. (AP PhotoOliver de Ros)

People without legal permission to be in Mexico leave an office of the Attorney General before being sent to Tapachula in an immigration van, as a member of the National Guard, left, stands watch in Arriaga, Mexico, Sunday, June 23, 2019. Mexico has completed its deployment of 6,000 National Guard agents to help control the flow of migrants headed toward the U.S. and filled immigration agency posts to regulate border crossings, the government said Friday. (AP PhotoOliver de Ros)

A man without legal permission to be in Mexico leaves an office of the Attorney General before being sent to Tapachula in an immigration van, as members of the National Guard stand watch in Arriaga, Mexico, Sunday, June 23, 2019. Mexico has completed its deployment of 6,000 National Guard agents to help control the flow of migrants headed toward the U.S. and filled  immigration agency posts to regulate border crossings, the government said Friday. (AP PhotoOliver de Ros)

A man without legal permission to be in Mexico leaves an office of the Attorney General before being sent to Tapachula in an immigration van, as members of the National Guard stand watch in Arriaga, Mexico, Sunday, June 23, 2019. Mexico has completed its deployment of 6,000 National Guard agents to help control the flow of migrants headed toward the U.S. and filled immigration agency posts to regulate border crossings, the government said Friday. (AP PhotoOliver de Ros)