WILMINGTON, Del. (Reuters) - A U.S. appeals court ruled on Tuesday that the Trump administration may continue sending asylum seekers to wait out their cases in Mexico while the government appeals a lower court ruling that found the policy violated U.S. immigration law.

The U.S. Court of Appeals for the Ninth Circuit in San Francisco found that a preliminary injunction barring the government from returning asylum seekers to Mexico was "unlikely to be sustained" on appeal in its present form and stayed the lower court ruling.

The Department of Homeland Security "is likely to suffer irreparable harm absent a stay because the preliminary injunction takes off the table one of the few congressionally authorized measures available to process the approximately 2,000 migrants who are currently arriving at the nation's southern border on a daily basis," the judges said in issuing the stay.

While asylum seekers may fear substantial injury upon being returned to Mexico, the judges said, "the likelihood of harm is reduced somewhat by the Mexican government's commitment to honor its international-law obligations and to grant humanitarian status and work permits to individuals returned."

The U.S. government was appealing an order by a U.S. District Court in early April that enjoined the policy, known as the Migrant Protection Protocols (MPP).

The program, launched in January, was one of many policies aimed at slowing rising numbers of immigrants arriving at the border, many of them families from Central America, that has swelled to the highest in a decade.

Since the policy went into effect on Jan. 29, through May 1 more than 3,000 Central Americans have been sent back to Mexico, according to Mexican officials.

The government argues that the MPP is needed because so many asylum seekers spend years living in the United States and never appear for their court hearings before their claim is denied and an immigration judge orders them to be deported.

Omar Jadwat, director of the American Civil Liberties Union's Immigrants' Rights Project, criticized the ruling. "Asylum seekers are being put at serious risk of harm every day that the forced return policy continues," he said.

Jadwat noted that two of the three judges who heard the appeal found "serious legal problems with what the government is doing, so there is good reason to believe that ultimately this policy will be put to a halt."

In recent years, there has been a shift in border crossings from mainly single, adult Mexicans trying to evade capture to Central American families and unaccompanied minors turning themselves in to border agents to seek asylum. Because of limits on how long children can be held in detention, most families are released to pursue their claims in U.S. immigration courts, a process that can take years.

(Reporting by Tom Hals in Wilmington, Delaware; Additional reporting by Lizbeth Diaz in Mexico City; Editing by G Crosse and Leslie Adler)