WASHINGTON (Reuters) - Democrats in the U.S. House of Representatives on Thursday said the Trump administration is blocking investigators from touring immigrant detention facilities nationwide after recent visits revealed what they called “serious ongoing problems” concerning how detainees are being treated.

Representative Elijah Cummings, chairman of the House Oversight and Reform Committee, said committee staff were barred from visiting 11 U.S. Customs and Border Protection facilities days after previous inspections found conditions that threatened the health and safety of the adult and child migrants being held, writing in a letter to Kevin McAleenan, the acting secretary for the Department of Homeland Security.

The administration, Cummings said, had also imposed new restrictions on visits to Immigration and Customs Enforcement (ICE) facilities that also house migrants, including a two-hour time limit.

The “last-minute denial of access” and the new restrictions “are unacceptable and impair the Committee’s ability to conduct its oversight responsibilities in an effective manner,” Cummings wrote.

During visits by committee staff last week, detainees expressed concerns about rotten food, inadequate clothing and substandard medical care, Cummings said. Some said they had been held by ICE for more than a year, he said.

At some facilities, committee staff were not permitted to speak directly with detainees and were not allowed to use their mobile phones to document conditions, Cummings said.

The Department of Homeland Security (DHS) did not immediately respond to a request for comment on the letter.

A report in July by DHS’ internal watchdog detailed squalid conditions at some detention facilities, including severe overcrowding and children going without hot food and showers for days.

The administration is struggling to contain a record surge in families fleeing violence and poverty in Central America. DHS officials say they have caught or rejected 475,000 family members in the past 10 months, more than three times any previous full year.

The department said this week it will divert $271 million in disaster-aid and cyber-security funds from the Federal Emergency Management Agency and other DHS entities in part to expand its migrant detention centers, prompting an outcry from Democrats as the U.S. mainland falls under threat from Hurricane Dorian.

Earlier this month, the Trump administration unveiled a rule that allows officials to detain migrant families indefinitely while judges consider whether to grant them asylum in the United States, abolishing a previous 20-day legal limit.

In addition, Trump recently said his administration was considering ending the right of citizenship for children born to non-citizens within the United States.

A group of House Democrats this year offered legislation, called the Public Oversight of Detention Act, that would require that members of Congress be granted access to detention centers within 48 hours of a request.

The bill stemmed from Democratic Representative Jason Crow of Colorado being denied entry to an Aurora, Colorado facility operated by GEO Group, amid reports of problems.