President Xiomara Castro announced the new project along with other emergency measures such as giving the military a greater role in tackling organised crime and prosecuting drug traffickers as terrorists.

The 20,000-capacity prison will be built in the country’s eastern province of Olancho.

President Castro’s policies are seen as a stark U-turn — the left-winger formerly had a more progressive stance on crime. But her administration is now asking the country’s congress to amend the penal code so that the authorities can detain suspected gang leaders without having to file charges or carry out mass trials.

In El Salvador, the government has had success in defeating the gangs which once controlled large parts of the country. In the past two years around 70,000 people, or two per cent of the adult population, have been jailed there. Most of those imprisoned were suspected of gang membership.