He pledged to make the Inquiry as “open and transparent as it is legally possible to be” and to “hold people to account where appropriate”.

He said: “It is not only the law, but a central principle of mine that this Inquiry… expresses its views at the end without fear or favour, affection or ill-will.”

The Inquiry would be “frightened of no-one in the conclusions it draws”, he added.

Victims, some of whose stories were shown in a film at the opening of the hearings, said they have been living “half lives” under the shadow of their illnesses.

Many told how they had been unable to work, their relationships had failed, they had been stopped from having children or forced into abortions and how they felt forced to hide their illness because of the stigma surrounding the diseases.

They called for the Inquiry to complete its investigations in as short as time as possible so that victims were still alive to hear its conclusions.

Nearly 100 victims are thought to have died since the Inquiry was announced in July last year.