Inmates at 'worst prison on Earth' must abide by same strict rule as Trump looks to send US citizens there

El Salvador's mega-prison built to house up to 40,000 inmates is referred to as CECOT, meaning the Centre for the Confinement of Terrorism.

Miguel Sarre, former member of the United Nations Subcommittee for the Prevention of Torture, described the prison as a 'concrete and steel pit', while many objections have been raised by human rights groups.

Attention on the prison have intensified after the Trump administration announced it had secured a deal with El Salvador to transfer foreign citizens who had been convicted in the US there for a fee.

The offer was made that CECOT would also take criminals who were US citizens or legal residents, though a US government official later said that there were not currently plans to send US citizens to the El Salvadorean prison.

That would be incredibly difficult to do on legal grounds, so for now the deal would appear to mean that foreign nationals in the US could be deported to El Salvador and imprisoned in CECOT.

Prisoners must follow strict rules. (MARVIN RECINOS/AFP via Getty Images)

It's not a particularly nice place at all, with a series of strict rules put in place that inmates are forced to follow.

Every inmate wears a white shirt and shorts, and they have their heads shaved every five days.

At night, inmates are forced to sleep in conditions described as 'inhumane', as within the prison's 'modules' over 100 inmates are kept in a room which contains two toilets, two sinks and 80 bunks to sleep in.

The beds themselves have no mattresses, meaning the CECOT prisoners have to sleep on hard metal, and besides 30 minutes of exercise, there is essentially nothing for the inmates to do besides read one of the two bibles in each of the crowded cells.

Mealtimes at the prison have been criticised as well, since inmates must eat with their hands and only get small portions of intentionally unappetising food.

Other than a short amount of time for exercise, prisoners have nothing to do all day but wait in their cells (MARVIN RECINOS/AFP via Getty Images)

CECOT is considered to be one of the highest security prisons in the world and very difficult to escape from, with the place criticised as somewhere people have been incarcerated without sufficient evidence to hold them.

Last year, when BBC correspondent Leire Ventas visited the prison, they noted the rows of prisoners with shaved heads stuck inside the prison some had called a 'black hole of human rights'.

Ventas noted that the lights in the prison were never turned off and have only a few air filters to cool a place where temperatures inside can reach 35C.

AP reported that according to the El Salvadorean justice minister, prisoners held in CECOT would never be allowed to return to their communities.