The US government is being sued by a group of detained asylum seekers who claim immigration officials in five southern states are systematically denying them parole.

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 centres in Alabama, Arkansas, Louisiana, Mississippi and Tennessee.

The plaintiffs include Central American migrants, a member of a Cameroonian opposition party and Cuban and Venezuelan political dissidents.

Under US law, migrants who arrive at US ports of entry and ask for refuge 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 US Immigration policy.

The suit, filed in US District Court in Washington 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 US immigration data cited in the case, the New Orleans Field Office – which oversees the five states – granted parole in 76 per cent of cases in 2016, but just 22 per cent in 2017.

In 2018, parole was granted in just two of the 130 cases in which ICE made a determination, or less than 2 per cent, the complaints say.

President Donald Trump, who has made immigration a focus 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 the practice of what he calls “catch and release” by detaining more asylum seekers during their court proceedings.

But US 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 US immigration officials decide to release them.

One of the migrants represented in the case is a transgender woman who said she fled police repression in Cuba and sought asylum in Texas, in January.

She has been detained since then and during months in custody, the suit alleges, she has been 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 immigration field offices in Detroit, Los Angeles, Philadelphia, El Paso, Texas, and Newark, New Jersey.

Last July, a US federal judge ordered the immigration department 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.