WASHINGTON — Mexico has agreed to allow the United States to restart a contentious asylum program that requires certain migrants to wait in Mexico until American immigration officials decide their cases — a new complication for the Biden administration’s fledgling efforts to remake the country’s immigration system after the restrictive policies of former President Donald J. Trump.

The Biden administration, which announced the agreement on Thursday, has tried to end the program, which American officials and advocacy groups have assailed as dangerous and inhumane. But it has been forced to restart it under a court order, and doing so requires the cooperation of the Mexican government, which had been reluctant to do so without commitments to address humanitarian issues. The program, known commonly as Remain in Mexico and formally as Migrant Protection Protocols, is expected to resume next week, according to The Washington Post, which earlier reported the agreement. Its asylum hearings will be held in tent courts in San Diego, El Paso and Brownsville, Texas.

At Mexico’s request, the United States has agreed to limit immigration proceedings to six months per asylum applicant. During the Trump administration, the Remain in Mexico cases could drag on for years in some cases, according to Biden administration officials who spoke on condition of anonymity to discuss the terms of the agreement. American officials also pledged to improve access to counsel before and when migrants denied asylum are returned to countries where they could face persecution, and to provide more information to migrants about the program.

The program was an early target of President Biden’s plan to rebuild an asylum system that had largely been dismantled under Mr. Trump. Restarting it was always going to be a bitter pill for the Biden administration. But its resumption, which involves placing more people in congregate settings, comes as the United States braces for the spread of a worrisome new coronavirus variant, called Omicron, that was detected in the country this week.

As part of the agreement with Mexico, the United States will offer Covid-19 vaccines to migrants in the program, the Biden administration officials said.

Critics say the program forced migrants to stay in unsanitary tent encampments where they faced sexual assault, kidnapping, torture and harsh weather. Under the new agreement, asylum applicants in the program will mostly be single adults who are less vulnerable to the waiting conditions than, for example, migrant families with young children, the officials said.

The program’s changes did not satisfy its critics. “This is a disaster waiting to happen,” Aaron Reichlin-Melnick, a policy counsel at the American Immigration Council, wrote in a Twitter post on Thursday.