A federal judge in New York on Tuesday ordered a significant improvement in the conditions of detention of migrants held by police in a building in midtown Manhattan, which their defenders deemed disgraceful.

Judge Lewis Kaplan, approached by migrant aid groups, issued an injunction concerning people held on the 10th floor of a tower that also houses a court responsible for immigration issues, 26 Federal Plaza.

For several weeks, police officers have been going there every day, masked, as they leave courtrooms, to arrest migrants forced to appear before the judicial authorities to assert their claims, particularly for asylum. A method described as a "trap" by their lawyers.

Once arrested, some are then held on the 10th floor, sometimes for several days, under the responsibility of the American immigration police (ICE).

However, clandestinely taken videos, relayed by the media and social networks, show people gathered in a single room, lying on the floor with survival blankets.

A man told The City newspaper that he watched helplessly as another man had an epileptic seizure for half an hour before medical help arrived. A 20-year-old student reported being forced to wear blood-soaked clothes for days because she didn't have sanitary towels.

In his decision, Judge Kaplan ordered the authorities to no longer detain people on this floor unless they are provided with a decent living space, clean mattresses to sleep on, rooms cleaned three times a day, basic hygiene products, and access to medication if necessary.

It also orders police to inform detainees that they have the right to make confidential and free legal calls, to request clean clothes and a private space to change, and to receive medication through a lawyer or family member.

This decision "sends a clear message: ICE cannot hold people in abusive conditions and deny them access to their constitutional rights," said Eunice Cho, a detainee defense attorney with the left-leaning ACLU. "We will continue to fight to ensure that people's rights are respected at 26 Federal Plaza and beyond."

The number of undocumented immigrants in the United States is estimated at around 11 million, and the number of their arrests and detentions has increased significantly in recent months.

Donald Trump has made the fight against illegal immigration a top priority, regularly referring to an "invasion" of the United States by "criminals from abroad."