Mexico says the United States has started returning more Central American migrants to Mexico in a unilateral move not coordinated with the government in Mexico City.

Under a plan that was implemented by the administration of US President Donald Trump in December last year, US authorities forced Central American migrants to return to Mexico pending the outcome of their asylum requests, which could take months, if not years.

That policy — which applies to non-Mexican migrants only — was until now being carried out at the San Ysidro port of entry in San Diego.

But the Mexican Foreign Ministry issued a statement on Tuesday announcing that the measure was now expanded to the Calexico port of entry in Southern California, too.

The ministry said “it does not agree with this unilateral measure implemented by the US authorities.”

It said it was in contact with US authorities about those who were scheduled to be returned but only for “humanitarian reasons.”

“This exchange of information does not in any way mean the government of Mexico agrees with the decisions and actions being taken unilaterally by the US government,” the Foreign Ministry said.

​A migrant waits with his children to apply for asylum in the United States, on the border with Mexico, on February 8, 2019. (Photo by AP)

Caravans of migrants from Central American countries have been traveling for months through various routes ending up in Mexico to reach the country’s border with the US, where they seek to apply for asylum and settle down.

But the Trump administration has been blocking them at the border with Mexico. Washington has also been separating migrant families or deporting those who have successfully crossed back to their home countries, where they face violence or economic difficulties.

Rights groups have condemned those practices. Amnesty International condemned the Trump administration policy in January as “disgraceful, mean-spirited and unlawful.”

Trump unveiled the plan last year as the caravans made their way to the US-Mexico border. He called the potential entry of the caravans an “invasion” by “thugs” and “criminals” and warned them to turn back or his administration would separate families at the border with Mexico.

He has long said he plans to build a wall along the US’s entire border with Mexico. While he had promised that funding for the wall would be provided by Mexico, he has failed to achieve that goal, and, also failing to secure funding from the US Congress, he has declared a national emergency to corral funding for his wall.