The U.S. government would take actions to force asylum seekers to stay in Mexico during their immigration proceedings, Secretary of State Mike Pompeo said in a statement on Thursday.

Individuals arriving in the United States from Mexico, illegally or without proper documentation, will be returned to Mexico for the duration of their immigration proceedings, said the statement.

Pompeo described this as a "historic action to confront the illegal immigration crisis", saying the Mexican government had been notified.

Mexican foreign ministry said on Thursday that it would authorize temporary entrance of individuals coming from the United States for humanitarian reasons.

The U.S. government has been actively engaging with the Mexican new government led by President Andres Manuel Lopez Obrador in dealing with mass migrants traveling from Central America via Mexico to U.S. southern borders.

U.S. President Donald Trump had categorized the migrant caravan as an "invasion" and ordered the Pentagon to deploy active-duty troops to the border in assistance to border security forces.

Some 2,500 migrants still stay along the U.S.-Mexico border, hoping to cross it, whether legally or illegally.