The deaths of a father and his toddler daughter whose bodies were pictured face down in a river after they tried to get to the US have sparked outrage.

:: Warning distressing images below

The tragedy comes amid a recent spate of other deaths on the US-Mexico border, which highlight the dangers facing Central American migrants along the route.

Harrowing photographs of El Salvador migrant Oscar Alberto Martinez Ramirez and his 23-month-old daughter Valeria show the little girl holding onto her father as their bodies lie side-by-side in shallow water along the bank of the Rio Grande on the Mexican side.

The man's black shirt is up around to his chest with the child tucked inside.

Valeria's arm is draped around his neck and it appears she clung close to him in the final minutes of their lives.

Their bodies were found on Monday morning near Matamoros, Mexico, across the water from Brownsville, Texas.

Image: The bodies were found face down in the Rio Grande on the US-Mexico border

The location was several hundred metres from where they had tried to cross the day before and just a half a mile from an international bridge.

According to Mexican paper Le Duc, Mr Ramirez had swum the river with his daughter and then left her on the US side to go back for his wife Tania Vanessa Avalos.

However Valeria panicked and tried to reach her father. But sadly both were swept away by the current.

A frustrated Mr Ramirez had reportedly decided to swim with his daughter because the family was unable to present themselves to US authorities and request asylum.

Image: The scene where the bodies were discovered on the Mexico side of the river

Image: Mr Ramirez's mother Rosa holds her granddaughter's favourite doll and stuffed animal

Back in El Salvador Mr Ramirez's mother Rosa, holding her granddaughter's favourite doll and stuffed animal, said the last message she had received from her son was on Saturday.

"He said 'mama, I love you'. He said 'take care of yourselves because we are fine here.' When I read that message, I don't know, it made me want to cry because I saw it as a sort of goodbye."

She has spoken with her daughter-in-law since the tragedy.

Rosa Ramirez said: "When the girl jumped in is when he tried to reach her, but when he tried to grab the girl, he went in further ... and he couldn't get out.

"He put her in his shirt, and I imagine he told himself, 'I've come this far' and decided to go with her."

Drowned man's final words to mum: 'I love you'

Ms Ramirez said her son and his family left El Salvador on 3 April and spent about two months at a shelter in Tapachula, near Mexico's border with Guatemala.

"I begged them not to go, but he wanted to scrape together money to build a home," she said. "They hoped to be there a few years and save up for the house."

The UN refugee agency, the UNHCR, said it was deeply shocked to see the "heart-breaking" photos of the two victims.

It pointed out the tragedy happened less than four years after the drowning of Syrian refugee toddler Alan Kurdi in the Mediterranean near Turkey.

His body was found on a beach and the image shocked EU leaders and led to increased concerns about the refugee crisis.

The UNHCR said on Wednesday: "We are once again confronted with powerful visual evidence of people dying during their dangerous journeys across borders."

Image: Mr Ramirez's father, Jose Martinez Carcamos, pictured in tears after the tragedy

Mexican President Andres Manuel Lopez Obrador said of the latest deaths: "Very regrettable that this would happen.

"We have always denounced that, as there is more rejection in the United States, there are people who lose their lives in the desert or crossing" the river.

US Democratic presidential candidate Beto O'Rourke, from the border city of El Paso in Texas, tweeted: "Trump is responsible for these deaths."

The 2,000-mile-long US-Mexico border has sometimes been a deadly crossing between ports of entry. A total of 283 migrant deaths were recorded last year. The death toll so far this year has not been released.

Two babies, a toddler and a woman were found dead on Sunday, overcome by the sweltering heat.

Elsewhere, three children and an adult from Honduras died in April after their raft capsized on the Rio Grande.

Image: John Sanders, the head of the US border protection, or ICE, has resigned

The spate of migrant deaths comes as John Sanders, the head of the US border protection, or ICE, resigned. He has not given a reason for his departure.

Mr Sanders said in a recent interview that the department's problems were to do with a lack of money, and he called on congress to pass a $4.5bn (£3.55bn) bill to address the so-called border crisis.

Democrats in the House of Representatives have already approved the humanitarian aid but the bill faces a tough route through the upper chamber, the Republican-controlled Senate.

President Donald Trump said he did not seek Mr Sanders' resignation and added he did not think he had ever met him.

Mr Trump says he is 'very concerned' about conditions for migrants

Mr Trump's hardline stance on immigration has come under intense scrutiny recently, as conditions inside border patrol facilities were found to be poor, with inadequate food and a lack of medical care.

At a migrant centre in Clint, Texas, lawyers found that several children had flu and a two-year-old without a nappy was being watched over by two older children.

They also saw children in soiled clothing, covered in urine and faeces, with many of them not having washed since they entered the facility weeks ago.

Image: Lawyers say they saw children wearing soiled clothes at the facility

Lawyers also reported children were "locked up in horrific cells where there's an open toilet in the middle of the room".

After the findings, an official said that nearly 300 children had been moved from the facility, but staff have since moved a third of those back into Clint.

Image: The facilities in Clint have been described as poor by lawyers visiting the site

Mr Trump has said he is "very concerned" over the conditions at the border, but claims things are better than they were under the previous administration.

Rebuking Mr Trump, Michael Bochenek, a lawyer for Human Rights Watch, said: "We did not have the kind of overcrowded conditions for unaccompanied kids in Border Patrol holding cells like we saw in Clint."