A day after U.S. government investigators warned of dangerous overcrowding and poor conditions at migrant facilities on the southwest U.S. border, President Donald Trump tweeted that many of the "illegals aliens" were living in better conditions than the places they left.

Trump has continued to push back against criticism of the migrant detention centres as U.S. lawmakers, officials and even his administration's own departmental watchdog have reported that cells are packed, people are being held for extended periods of time and children lack access to showers and hot meals.

Trump also blamed Democrats for the conditions that have proliferated under his hardline stance against illegal immigration.

Democrats, meanwhile, sharpened their attacks on the Trump administration's handling of the migrant crisis on the U.S.-Mexico border, saying Wednesday that human rights were being neglected and demanding the firing of the Border Patrol's leadership.

"How can anybody look at these photos and think this isn't a human rights abuse?" U.S. Senator Kamala Harris, a candidate for the 2020 Democratic presidential nomination, wrote on Twitter on Wednesday.

Our Border Patrol people are not hospital workers, doctors or nurses. The Democrats bad Immigration Laws, which could be easily fixed, are the problem. Great job by Border Patrol, above and beyond. Many of these illegals aliens are living far better now than where they..... —@realDonaldTrump

Democratic U.S. Rep. Joaquin Castro, who visited detention centres in Texas this week, said migrants had been deprived of baths and showers for at least two weeks and of their medication for days, and were locked in areas with broken water faucets.

"It's clear that their human rights were being neglected," he told reporters during a conference call that included other lawmakers who had been on the visit.

Trump dismissed the Democrats' criticism and said the crisis at the border could be fixed if migrants only came into the United States legally.

The Department of Homeland Security's inspector general issued a report Tuesday that raised concerns for the health and safety of detainees and agents, warning the overcrowding represented a "ticking time bomb."

Along with the report, the DHS watchdog also published photos following visits by its auditors to five U.S. Customs and Border Protection (CBP) agency facilities in the Rio Grande Valley area during the week of June 10. Photos provided in the report were digitally manipulated to obscure the faces of the detainees.

The report also featured this image of some of the 51 adult women held in a cell built to hold 40 male juveniles pressing against the cell window at the Fort Brown Border Patrol station in Brownsville, Texas. (Office of Inspector General/DHS/Handout via Reuters)

Conditions at the centres have been a flashpoint since May, when the watchdog warned of similar conditions at facilities in the El Paso sector in Texas, with migrants held for weeks instead of days and adults kept in cells with standing room only.

Security incidents among men at facilities in the Rio Grande Valley included detainees clogging toilets in order to be released from cells, migrants refusing to return to cells, and special operations teams brought in to show that Border Patrol was prepared to use force, the report on Tuesday said.

Migrants banged on cell windows and shouted when investigators visited. Most single adults had not had a shower despite several being held as long as a month. One photo showed a man in a packed cell holding a message reading: "Help 40 Day[s] Here."

Border Patrol agents under scrutiny

Also Wednesday, the U.S. Department of Homeland Security's acting secretary, Kevin McAleenan, ordered an investigation into reports Border patrol agents have been posting offensive anti-immigrant comments and threats against lawmakers in a secret Facebook group.

"Reporting this week highlighted disturbing & inexcusable social media activity that allegedly includes active Border Patrol personnel," he wrote on Twitter on Monday, calling the reported comments "completely unacceptable."

He said any employee found to have "compromised the public's trust in our law enforcement mission will be held accountable."

An image of an overcrowded area holding families at a Border Patrol station in Weslaco, Texas, was also released as part of the report. (Office of Inspector General/DHS/Handout via Reuters)

The Facebook posts, first reported by the non-profit news site ProPublica, included jokes about the deaths of migrants and sexually explicit content referring to Rep. Alexandria Ocasio-Cortez, a Democrat who was highly critical of the detention facilities after a tour this week.

Democratic Senate minority leader Chuck Schumer issued a statement calling for the firing of the acting head of the CBP and other top leaders at the agency as a first step to reining in a "toxic culture" there.

"The horrid conditions CBP has subjected children and families to at the border are nothing short of inhumane and downright inexcusable," Schumer said.



Dr. Sara Goza, the incoming president of the American Association of Pediatrics, toured CBP facilities in McAllen, Texas, last week and described the rooms where children were being detained as reeking of sweat, urine and feces.

The AAP also shared images of drawings made by children recently released from CBP custody. The drawings, which depicted the children being held in cages, were provided by a social worker in Texas.

Report details potential violations of federal law

Pediatricians called again on border authorities to accept their offer to provide volunteer medical care to migrants in detention. CBP rejected the offer.

Roger Maier, a CBP spokesperson, said anyone who needs medical attention beyond what government and contract staff can provide is taken to a local hospital.

The Rio Grande Valley is the busiest area of the border for migrant arrests, which hit a 13-year monthly high in May during a surge in the arrival of Central American families. At the time of the investigators' visits, U.S. Border Patrol was holding some 8,000 detainees in custody in the Rio Grande Valley sector, with 3,400 held longer than the 72 hours permitted.

The Democratic chair of the House of Representatives committee on oversight and reform said the panel had invited the acting heads of the Department of Homeland Security and CBP to testify on July 12 on the administration's border policies, including the conditions of children at detention centres.

Trump has made a crackdown on illegal immigration a centrepiece of his domestic policy agenda and 2020 re-election bid. But his efforts to build a wall on the southern border have been blocked in Congress, and he was forced last year to backtrack after his "zero tolerance" border policy of separating migrant children from their parents provoked widespread outrage.

The report warns that facilities in South Texas' Rio Grande Valley face 'serious overcrowding' and require 'immediate attention.' (Office of Inspector General/DHS/Handout via Reuters)

Trump's quest for a border wall received another blow Wednesday when an appeals court upheld a freeze on Pentagon money to build it. Trump had rejected border security bills approved by Congress and instead declared a national emergency earlier this year and said he would free up billions of dollars from the Pentagon to build high-priority sections of wall in Arizona and New Mexico.

The Border Patrol made 132,887 apprehensions in May, including 84,542 adults and children travelling together. With long-term facilities for adults and children at capacity, Trump's administration has said it has to hold people in unsuitable Border Patrol facilities for much longer than the 72 hours normally allowed by law.

The auditors' report detailed several potential violations of federal law or Border Patrol standards: