WASHINGTON - The Biden administration is set to tighten access to asylum at the U.S.-Mexico border via a new regulation that could be issued as soon as Thursday, four sources familiar with the matter said, in a targeted move aimed at reducing illegal crossings.

The regulation would require migrants to be assessed at an initial asylum screening stage to see whether they should be barred from asylum and quickly deported, said the sources, who requested anonymity to discuss internal government planning. They added that the measure appeared limited in scope.