Declassified British government documents reveal the existence of a secret interrogation centre in Ballykelly, Co Derry in the early 1970s.

Twelve internees were subjected to violent ill-treatment, which led the then government to take a case to the European Commission of Human Rights on behalf of the men.

It is claimed London misled two official inquiries and the European Court of Human Rights about the existence of the centre and its operations.

On 9 August 1971, nearly 350 people were arrested and interned in Northern Ireland.

Twelve men were subjected to deep interrogation known as the five techniques, which the European Commission of Human Rights described as torture.

The Pat Finucane Centre has uncovered the declassified documents showing that the location of the interrogation centre at Ballykelly was a closely kept secret.

In the case brought to the European Court of Human Rights by the government against London in the 1970s, there was no mention of an interrogation centre at Ballykelly.

The Pat Finucane Centre claims London misled two official inquiries and the European Court of Human Rights.

Speaking on RTÉ’s Morning Ireland, Sara Duddy of the Pat Finucane Centre said the documents had uncovered the use of techniques such as hooding, sleep deprivation, diet restrictions, white noise and other methods on detainees at the Derry centre.

She said the Centre had cross-referenced this new information with the contents of previous inquiries, such as the 1971 Compton Report and the Parker Report one year later.

The Compton Report looked into alleged use of brutality by security forces in Northern Ireland, while the Parker Report investigated interrogation methods against terror suspects.

Based on that study, she questioned whether either of these inquiries had been informed of the existence of the centre at Ballykelly.

Ms Duddy also said that an ECHR probe into similar treatment of detainees also seemed to be unaware of the use of these methods at the Ballykelly centre.

The Department of Foreign Affairs in Dublin is examining the matter.