Outrage is growing in Mexico following a fire at a migrant centre in Ciudad Juárez that killed 38 migrants.

Footage has emerged which shows the moment the fire started at the centre run by Mexico's National Migration Institute (INM).

Uniformed officials seem to walk away as the blaze erupts in a corner, leaving a group of men behind in what appears to be a locked cell.

The men unsuccessfully try to open the barred door as smoke quickly spreads.

The BBC verified the footage by reverse searching the thumbnail and seven frames from the 32-second video and found no copy of it before Tuesday evening, indicating the footage is recent.

It also spoke to Alejandra Corona, a co-ordinator for the Jesuit Refugee Service in Ciudad Juárez, who visits the facility weekly.

She said the view seen on the video was consistent with the location of a security camera at the entrance to the men's detention area.

Ms Corona explained that the migrant centre - located just south of the bridge which links Ciudad Juárez with the city of El Paso in Texas - houses offices where migrants are processed, as well as areas where they can be detained.

She described the area behind bars that can be seen in the footage as "a cell".

"The door has always been locked when we have visited [this area], and even when come to speak to the migrants, they can't come out, we have to stay on the outside," she explained.

"I am not aware of an emergency exit, as far as I know the door you can see in the video is the only exit."

Ms Corona said that on her visits the cell, which usually holds between 40 and 60 men, has been watched over by a private security guard and a staff member of the INM, which squares with the two uniformed men who can be seen in the footage.

The footage has been widely shared on Twitter and published by a number of Mexican newspapers, with many people expressing shock at what they said was a failure by the uniformed staff to act.

They point to the moment at which one of the men in uniform seems to ignore a man behind the barred door, who appears to try to open it and fails as the flames spread.

As the video has no sound it is not possible to ascertain what, if anything, was said as the fire erupted. It is also unclear what the uniformed staff are doing when not on camera.

The smoke then fills the room making it hard to make out anything beyond the glare of the flames.

The footage appears to back up the account of the wife of a Venezuelan migrant who survived the fire.

Viangly Infante Padrón told reporters that officers had left her husband and the other male migrants "behind locked bars" as they fled.

"There was smoke everywhere. They let the women out and the migration staff, but it wasn't until the firefighters arrived that they let the men out," she told Associated Press news agency.

She also said that the men had been protesting because they had not been given any water while in custody.

On Monday, Mexican President Andrés Manuel López Obrado said the migrants set mattresses alight "when they learned that they'd be deported".

On Tuesday, he said a thorough investigation would be carried out and vowed there would be "no impunity and no one will be protected".

Mexican officials say a total of 68 men were in the facility at the time of the blaze. The majority were from Guatemala with the others from Colombia, Ecuador, El Salvador, Honduras and Venezuela.

Mexican officials have released the names of all the men but have not yet provided clarification as to which of them are dead and which have survived.

They also revised the number of dead down from 40 to 38, while 28 are reported to be seriously injured and suffering from smoke inhalation.

Distraught relatives have complained about not being given enough information about the fate and whereabouts of their loved ones.

Even an updated list of casualties still contained erroneous information, further heightening the anxiety among those waiting for news, Ms Corona of the Jesuit Refugee Service said.

The relatives also queried why the men had been locked up in the first place.

Ms Corona told the BBC that raids to detain migrants had become more frequent in Ciudad Juárez. "Anyone who enters Mexico in an irregular way can face arrest."

She added it was important to note that that did not mean that those held at the facility had committed any crime.

"Their relatives told us that some had been detained upon landing at the airport, others at the bus terminal and yet others on the streets of the city," Ms Corona explained.

The fire comes at a time when Mexico is struggling to deal with an influx of migrants, most of whom are crossing Mexico in the hope of reaching the United States.

Many of them have been camped out in cities on the US-Mexico border for weeks and sometimes months, awaiting the possible lifting of a Trump-era policy that allows US border officials to deny individuals entry to the US "to prevent the spread of communicable diseases".

The Biden Administration had moved to end the policy, which is known as Title 42, last year, but the US Supreme Court blocked the move at the end of December and it remains in place.

However, many migrants from Central and South America, as well as from as far afield as Africa, continue to embark on long treks to the US-Mexico border in the hope of the restrictions being lifted.