MEXICO CITY — Mexico’s top diplomat said Thursday his country expects to see “constant and growing” flows of migrants in coming years and estimated the United States must spend $2 billion per year in development aid to stem the tide.

Foreign Relations Secretary Marcelo Ebrard said Mexico has proposed investing money in Honduras, Guatemala and El Salvador and expects the United States to join that effort. Those three Central American countries have been sending the largest number of migrants to the U.S. southern border.

Mexico says the U.S. Needs to Allocate $2 Billion a Year for Immigration

“If you look at the region from different points of view, but especially demographics and economics, it is clear the flows are going to be constant and growing in coming years,” Ebrard said.

“The United States will have to allocate $2 billion per year for development in these countries, in Honduras, Guatemala and El Salvador,” he added.

The U.S. Border Patrol had 168,195 encounters with migrants last month, the highest since March 2001.

Mexico’s reluctance to take back Central American families with young children, especially in Tamaulipas state bordering the Rio Grande Valley, has resulted in many of them being released in the U.S. while their claims are considered by immigration authorities.