US President Joe Biden has issued an executive order to ramp up measures to prevent asylum seekers from entering via the country's border with Mexico.
"I'm announcing actions to bar migrants who cross our southern border unlawfully from receiving asylum," Biden said in Washington on Tuesday.
"Migrants will be restricted from receiving asylum at our southern border unless they seek it after entering through an established lawful process."
The US president went on to say that "asylum will still be available" to those who try to enter the US legally.
"But if an individual chooses not to use our legal pathways, if they choose to come without permission and against the law, they'll be restricted from receiving asylum and staying in the United States."
"This ban will remain in place until the number of people trying to enter illegally is reduced to a level that our system can effectively manage," Biden continued.
The White House earlier in the day published a presidential decree according to which migrants could be denied the chance to claim asylum in certain circumstances. This was criticized by both human rights activists and Republicans.
Those affected by the decree are to be deported at short notice if they do not explicitly request asylum. Those who do so will be subject to stricter checks by border officials.
Previously, most asylum seekers were generally allowed to stay in the country until their court date - which is often years in the future due to overburdened authorities.
Exceptions to Biden's decree are to apply to unaccompanied children and people who are seriously ill, as well as victims of human trafficking, among others.
The new regulation is set to apply as soon as the average number of illegal border crossings in a week exceeds 2,500 per day. The measures would then be dropped once the number falls below 1,500 again.
As the number of daily entries is currently above the new threshold, the measures are set to come into force on Wednesday.
Mexico is a transit country on the route taken by many Latin Americans fleeing from violence, poverty and political chaos at home trying to reach the US.