The policy, known as Title 42, is set to expire at midnight on May 11, prompting a rush of migrants to the border, now huddled under black plastic or makeshift tents waiting to cross into the US.

“Nothing like this has been seen before,” said Enrique Lucero, Tijuana’s director of migrant affairs.

Activists say that queues of migrants started arriving this week to the city of Tijuana, which borders San Diego, California, hoping to get ahead of a potential rush in asylum applications after May 11.

Some have attempted to cross illegally instead of waiting, they add.

The US has insisted the end of Title 42 does not mean borders will be open.

Mexican president Andres Manuel Lopez Obrador said yesterday he will hold a video call with his US counterpart Joe Biden today, with migration among the key topics to be discussed.

The Biden administration and Texas state government are sending reinforcements to the border to prepare for a possible increase in illegal immigration