US vice president Mike Pence has defended the Trump administration's treatment of migrants on a tour of detention facilities at the country's southern border.

Mr Pence visited two detention centres on Friday following reports of inhumane conditions.

He started with a border station in Donna, a vast collection of air-conditioned, interconnected tents built in May to temporarily handle 1,000 migrants and currently holding 800.

Later in the day, Mr Pence visited an outdoor portal at the McAllen border station, where 384 single men were being held in cages with no beds.

When reporters toured the facility before Mr Pence, the men said that they had been held there 40 days or more.

'Dangerous' overcrowding of migrants in US border facilities Show all 6 1 /6 'Dangerous' overcrowding of migrants in US border facilities 'Dangerous' overcrowding of migrants in US border facilities Photos of detained migrants crowded into cells at the US border - with one holding up a sign reading simply "help" - have been released as part of a new report warning of "dangerous" overcrowding. The memo was sent to the Department of Homeland Security by its Inspector General, containing photos taken at border facilities in the Rio Grande Valley over a week in June DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Eighty-eight adult males held in a cell with a maximum capacity of 41, some signalling prolonged detention to OIG Staff on June 12 DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Overcrowding of families observed by OIG on June 11, at a border patrol facility in Weslaco, Texas DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Migrant families overcrowding a border patrol facility on June 11 in McAllen, Texas DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Fifty-one adult females held in a cell designated for male juveniles with a capacity for 40 at Border Patrol’s Fort Brown Station DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Migrant families overcrowding a border patrol facility on June 11 in McAllen, Texas DHS/OIG

The detainees said they were hungry and wanted to brush their teeth. It was sweltering hot, but the only water was outside the fences and they needed to ask permission from the border patrol agents to drink.

"I was not surprised by what I saw," Pence said later at a news conference. "I knew we'd see a system that was overwhelmed."

He added: "This is tough stuff."

The vice president's office said it specifically instructed the border patrol agents not to clean up or sanitise the facility beyond what is routine so the American people could see the overcrowding and scarce resources, and and see how serious the crisis is at the border.

"That's the overcrowding President Trump has been talking about. That's the overwhelming of the system that some in congress have said was a manufactured crisis," Mr Pence said during a news conference after visiting the second facility.

"But now I think the American people can see this crisis is real."

Mr Pence's comments were at odds with recent statements from Republicans, as well as Donald Trump, who have accused Democrats who have visited similar facilities of exaggerating the poor conditions.

Mr Trump called recent media reports and comments from Democrats about poor conditions "phony".

And earlier this month, the US president downplayed concerns about how migrants are being treated at the facilities.

"Many of these illegals aliens are living far better now than where they came from, and in far safer conditions," Mr Trump tweeted on 3 July.

Mr Pence said the tough conditions are why the administration recently requested and congress approved $4.6bn (£3.7bn) in aid for the border, and he accused Democrats of not supporting more funding for additional beds at facilities for migrants.

He also defended the job being done by the employees at the detention centres.

"I was deeply moved to see the care that our customs and border protection personnel are providing," Mr Pence said.

"Coming here, to this station, where single adults are held, I've equally been inspired by the efforts of customs and protection doing a tough job in a difficult environment."

Mr Pence's visit was the latest move by both political parties to use border trips to highlight their case for who is at fault for the border crisis caused by a surge in Central American migrants and what should be done to remedy it.

Republicans have accused Democrats of failing to get on board with legal changes to the asylum system that would make the flow of migrants easier to handle, while Democrats have accused Mr Trump's policies and rhetoric of making a bad situation worse.

Mother of toddler who died in migrant detention centre speaks about conditions at border facilities

The political fight over the border is likely to only intensify as both parties prepare for the 2020 presidential race, in which immigration will be a top issue.

Border officials sought to counter some of the men's claims at the second facility Mr Pence visited.

Michael Banks, the patrol agent in charge of the McAllen facility, said the men there are allowed to brush their teeth once a day and are given deodorant after showering. But he conceded that many of the men had not showered for 10 or 20 days because the facility previously did not have showers.

There were no beds for them to sleep on because there wasn't room, Mr Banks said. Instead, they are each given a thermal blanket. He said they are also given three hot meals a day, along with juice and crackers.

After he toured the first facility, Mr Pence described a much better situation than the one that has been relayed by Democrats and in news reports.

He said Mr Trump wanted him there with media cameras to see for themselves how people were being treated.

"Every family I spoke to said they were being well cared for, and that's different than some of the harsh rhetoric we hear from Capitol Hill," Mr Pence said. "Customs and border protection is doing its level best to provide compassionate care in a manner the American people would expect."

Mr Pence first toured the cavernous facility built in May to handle overcrowding, where 800 people are living. Most were lying on napping mats on the floor, covered with thin, tinfoil blankets. In another room, children, all under 8 years old, were seated in front of a television watching an animated Spanish film.

Mr Pence asked the children if they had food and were being taken care of. They all nodded, and some said "si". A few children shook their heads no when asked if they had a place to "get cleaned up".

As Mr Pence toured the facilities, a House committee was having a contentious, partisan debate back in Washington over how migrants have been treated. Congresswoman Alexandria Ocasio-Cortez requested to be sworn in when appearing as a witness before the panel to show she was telling the truth when she retold a story about a migrant woman who said she had to drink water from the toilet because her sink broke.

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Congressman Chip Roy accused her of playing to her millions of Twitter followers.

Some Democrats have described the detention centres as "concentration camps" and say the US government is holding children in "cages". Several children have died after crossing the border and being taken into federal custody.

Mr Pence said it was "heartbreaking" to hear from children who had walked two or three months to come to America and cross the border illegally, but he ultimately blamed congress for failing to pass legislation that would deal with the influx of migrants at the southern border.