SAN DIEGO — A federal judge on Monday ordered a temporary halt to any deportations of immigrant families who were reunited after being separated by the Trump administration at the border.

US District Judge Dana Sabraw imposed a delay of at least a week after a request from the American Civil Liberties Union, which cited ‘‘persistent and increasing rumors . . . that mass deportations may be carried out imminently and immediately upon reunification.’’

Justice Department attorney Scott Stewart opposed the delay but did not address the rumors in court. He said he would respond later in writing. The judge gave the department until next Monday.

Late last month, Sabraw ordered the government to reunite thousands of children and parents who were forcibly separated in recent months under the Trump administration’s ‘‘zero tolerance’’ policy toward those who illegally cross into the United States.

He set a deadline of July 10 for roughly 100 children under age 5 and gave the government until July 26 to reunite more than 2,500 older youngsters.

The Trump administration reunited about half the under-5 children by last week, saying that in many of the remaining cases, the adults had criminal records or were determined not to be the youngsters’ parents.

In asking for a delay in deportations, the ACLU said parents need a week after being reunified with their children to decide whether to pursue asylum.

The decision ‘‘cannot be made until parents not only have had time to fully discuss the ramifications with their children, but also to hear from the child’s advocate or counsel, who can explain to the parent the likelihood of the child ultimately prevailing in his or her own asylum case if left behind in the US (as well as where the child is likely to end up living),’’ the ACLU said.

Late Friday, the judge said he was having second thoughts about whether the government was acting in good faith, after the Trump administration warned that speeding up the reunification process by dropping DNA testing could endanger children.

But on Monday, Jonathan White of the Office of Refugee Resettlement, who is overseeing the government’s effort, assured the judge that some reunifications of older children have occurred, and ‘‘it is our intent to reunify children promptly.’’ He went into detail on how the process was working.

Sabraw praised White, saying his testimony on the reunification plan gave him great comfort. ‘‘What is in place is a great start to making a large number of reunifications happen very, very quickly,’’ the judge said.

Justice Department attorneys also assured Sabraw the children were well cared for, offering him a visit to a shelter if he wanted.

The judge replied that the main concern wasn’t whether they were well cared for.

‘‘Obviously the concern that has been at issue has been the passage of time,’’ he said. ‘‘No matter how nice the environment is, it’s the act of separation from a parent, particularly with young children, that matters.’’

Sabraw has scheduled three more hearings over the next two weeks to ensure compliance with his order.

As part of the Trump administration’s broader crackdown on immigration, Attorney General Jeff Sessions recently tightened the restrictions on the types of cases that can qualify someone for asylum.

The change is making it harder for Central Americans who say they are fleeing the threat of gangs, drug smugglers, or domestic violence to pass even the first hurdle for securing US protection.

Immigration lawyers say that’s meant more asylum seekers failing interviews with US Citizenship and Immigration Services to establish credible fear of harm in their home countries.

They also say that immigration judges, who work for the Justice Department, are overwhelmingly signing off on those recommendations during appeals, effectively ending what could have been a yearslong asylum process almost before it’s begun.

‘‘This is a direct, manipulated attack on the asylum process,’’ said Sofia Casini of the Austin nonprofit Grassroots Leadership.

Casini’s group has been working with immigrant women held at the nearby T. Don Hutto detention center who were separated from their children under a widely condemned policy that President Trump ended on June 20.

Casini said that of the roughly 35 separated mothers her group worked with, more than a third failed their credible fear interviews, which she said is about twice the failure rate of before the new restrictions took effect.

Nationally, more than 2,000 immigrant children and parents have yet to be reunited.

In order to qualify for asylum, seekers must demonstrate that they have a well-founded fear they'll be persecuted back home based on their race, religion, nationality, membership in a particular social group, or political opinions.

The interviews with USCIS asylum officers, which typically last 30 to 60 minutes, are sometimes done by phone. Any evidence asylum seekers present to support their claims must be translated into English, and they often don’t have lawyers present.

The agency has funding for 687 asylum officers this fiscal year, but only about 510 are working at field offices nationwide. About 75 percent of ­USCIS’ asylum staff members were on detail to detention facilities in border states at the end of June.

In 2010, the Obama administration began allowing many immigrants passing credible fear interviews to remain free while their asylum cases progressed. The number of asylum seekers spiked, with federal authorities referring nearly 92,000 people for credible fear interviews during the 2016 fiscal year, compared with about 5,000 nine years earlier.