The Biden administration is urging migrants trapped in Mexico under restrictions imposed by former US President Donald Trump to be patient, even as the population of a refugee camp in north-eastern Mexico begins to swell with hopeful asylum seekers.

On Friday, a senior aide to US President Joe Biden said the administration is working on a system to process the tens of thousands of asylum seekers who have been forced to wait in Mexico under a Trump-era programme.

“We're reviewing now how we can process the migrants who are already in this programme,” the aide, Roberta Jacobson, said on a call with reporters. “How to prioritise the people who were enrolled not only months but years ago, and above all, people who are the most vulnerable.”

Jacobson said all of those waiting in Mexico under the programme, officially known as Migrant Protection Protocols (MPP),will have an opportunity to present asylum claims.

‘Please, wait’

The protocols, in place since 2019, have pushed more than 65,000 asylum seekers back into Mexico to wait for their US court hearings. The Biden administration stopped adding people to MPP last week, but has not yet outlined how it will process the claims of those already enrolled.

Advocates have documented the dangers they face while waiting, including rape and murder.

Jacobson promised that the administration would process people “in a much more rapid manner than in the past.”

She asked asylum seekers not to rush to the US border, however, as it would not speed up the process. “Please, wait,” she said.

Growing population at makeshift camp

The population of a makeshift refugee camp in the Mexican border city of Matamoros, across the river from Brownsville, Texas, has been slowly swelling, migrants and aid workers say, despite attempts by Mexican authorities to control it.

“It’s been growing because people think that if you're in the camp, you'll be able to enter (the United States) first,” said Honduran asylum seeker Oscar Borjas, who helps coordinate the camp. He estimated up to 800 people, including many women and children, are now living in the camp.

He and other camp residents welcomed Jacobson's comments.

“Everything is changing for the better,” said Dairon Elisondo, an asylum seeker and doctor from Cuba, who has been providing medical care to fellow migrants.