(Reuters) - A group of detained asylum seekers sued the U.S. government on Thursday claiming immigration officials in five southern states are systematically denying them parole.

FILE PHOTO - An ICE officer is seen at Otay Mesa immigration detention center in San Diego, California, U.S. May 18, 2018. REUTERS/Lucy Nicholson

In the second lawsuit of its kind filed against the Trump administration, legal advocacy groups representing 12 plaintiffs are seeking class action status on behalf of hundreds of asylum seekers being held in detention centers in Alabama, Arkansas, Louisiana, Mississippi and Tennessee. In addition to Central American migrants, the plaintiffs include a member of a Cameroonian opposition party and Cuban and Venezuelan political dissidents.

Migrants who arrive at U.S. ports of entry and ask for refuge in the United States are not eligible for bond hearings in front of a judge, but they can be released from detention on parole for humanitarian reasons under a 2009 U.S. Immigration and Customs Enforcement (ICE) policy.

The lawsuit, filed in U.S. District Court in Washington, D.C., by the American Civil Liberties Union and the Southern Poverty Law Center, claims that in recent months there has been an “unwritten policy and practice of categorically denying parole to asylum seekers” that violates the government’s “own directive and guidelines.”

According to ICE data cited in the complaint, the New Orleans Field Office - which oversees the five states - granted parole in 76% of cases in 2016, but just 22% in 2017. In 2018, parole was granted in just two of the 130 cases in which ICE made a determination, or less than 2%, the complaint said.

The Justice Department declined to comment. The Department of Homeland Security did not immediately respond to a request for comment.

President Donald Trump, who has made immigration a centerpiece of his administration, has said migrants are abusing the asylum system by making fraudulent claims to stay in the country for months or years as their cases work their way through a backlogged immigration court system.

He has pledged to end a practice of what he calls “catch and release” by detaining more asylum seekers during their court proceedings.

U.S. officials say the system is overwhelmed by thousands of migrants - mostly from Central America - claiming fear of returning to their home countries. Families are often released to live in the United States because of limits placed on how long children can be held in detention, but adults can be locked up indefinitely during their court cases unless ICE decides to release them.

ICE expanded its detention capacity this year by 2,500 beds in three facilities in Louisiana, where many of the plaintiffs are being held.

One plaintiff in the lawsuit is a transgender woman who said she fled police repression in Cuba, sought asylum in El Paso, Texas, in January and has been detained since. During months in ICE custody, the suit alleges, she said she was periodically held in isolation and has yet to receive an interview to be considered for release.

A separate lawsuit filed in March 2018 made similar claims about ICE field offices in Detroit, Los Angeles, Philadelphia, El Paso, Texas, and Newark, New Jersey. Last July, a federal judge ordered ICE to follow its own policy and grant parole to asylum seekers who are not a flight risk or a danger to the community in those jurisdictions.