WASHINGTON/NEW YORK — Democrats sharpened their attacks on the Trump administration's handling of the migrant crisis on the US-Mexico border on Wednesday, saying human rights were being neglected and demanding the firing of the Border Patrol's leadership.

US lawmakers, officials and rights activists who have visited migrant detention centers along the border describe nightmarish conditions marked by overcrowding and inadequate access to food, water and other basic necessities.

The Department of Homeland Security's inspector general on Tuesday described dangerous conditions in migrant-holding centers in Texas' Rio Grande Valley, publishing graphic photos of cells holding twice as many people as they were built for.

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

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

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

President Donald Trump, who has made clamping down on illegal immigration a key part of his domestic agenda, dismissed the Democrats' criticism and said the crisis at the border could be fixed if migrants only came into the United States legally.

"Our Border Patrol people are not hospital workers, doctors or nurses," Trump said on Twitter. "Great job by Border Patrol, above and beyond. Many of these illegals (sic) aliens are living far better now than where they ... came from, and in far safer conditions."

Scrutiny of the US Customs and Border Protection agency has intensified in recent days after reports that current and former agents had posted offensive anti-immigrant comments and targeted lawmakers on a private Facebook group.

Acting DHS chief Kevin McAleenan on Wednesday ordered an investigation, describing the reported comments as "disturbing" and "completely unacceptable." He said any employee found to have "compromised the public's trust in our law enforcement mission will be held accountable."

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 US Representative 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 reigning 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.

The White House on Wednesday attacked a ruling by a federal judge in Seattle who on Tuesday blocked an administration move to keep thousands of asylum seekers in custody while they pursued their cases.

"The district court's injunction is at war with the rule of law," White House press secretary Stephanie Grisham said in a statement. "The decision only incentivizes smugglers and traffickers, which will lead to the further overwhelming of our immigration system by illegal aliens."

The American Civil Liberties Union and other immigrant rights groups sued the government in April after Attorney General William Barr concluded that asylum seekers who entered the country illegally were not eligible for bond.

Tuesday's ruling by US District Judge Marsha Pechman said migrants cannot be denied a bond hearing that could give them a shot at release from detention while they fight their asylum cases.

Pechman's injunction blocked the implementation of a policy that was due to take affect July 15.

The ruling was another setback for Trump's immigration policies.

Congress has blocked Trump's efforts to get funding to build a wall on the southern border and he was forced last year to backtrack after his "zero tolerance" border policy of separating migrant children from their parents provoked widespread outrage.

But the record surge of mostly Central American families at the US southwestern border has begun to ease after tougher enforcement efforts in Mexico, according to Mexican and US officials.

Mexico's government, citing unpublished US data, said migrant arrests at the border fell 30 percent in June from the previous month after it started a migration crackdown as part of a deal with the United States to avoid possible trade tariffs.

The Mexican government said it was now busing home dozens of Central American migrants from Ciudad Juarez, across the border from El Paso, Texas, who were forced to wait in Mexico for their asylum claims to be processed under a US policy known as "Remain in Mexico."

After migrant arrests reached a 13-year monthly high in May, immigration has arguably become the biggest issue for Trump and the Democratic contenders vying for the chance to face him in the presidential election next year.

US Senator Cory Booker would "virtually eliminate immigration detention" if he wins the White House, his campaign said on Tuesday.

Presidential hopeful Julian Castro, the brother of Joaquin Castro, last week proposed decriminalizing border crossings as a step toward freeing up federal resources and eliminating thousands of cases clogging criminal courts - an initiative favored by Senator Elizabeth Warren, who is also running for the Democratic nomination.

Trump, meanwhile, looked to stir up support for his policies, promising immigration raids after the July 4 US holiday to arrest migrants with deportation orders. — Reuters