Allegations of abuse at Kincora Boys' Home will be examined when a long-running public inquiry reconvenes later.

The Historical Institutional Abuse (HIA) Inquiry will hear evidence from former residents of the notorious east Belfast facility where it is claimed a high-ranking paedophile ring preyed on vulnerable boys during the 1970s.

There have also been claims the UK security services knew about the abuse but did nothing to stop it, instead using the information to blackmail and extract intelligence from the influential men, including senior politicians, who were the perpetrators.

The HIA inquiry was set up by the Northern Ireland Executive in 2013 to examine harrowing allegations of physical, emotional and sexual abuse at state and church run residential institutions between 1922 and 1995.

It is being chaired by retired High Court judge Sir Anthony Hart who is sitting alongside Geraldine Doherty, a former head of the Central Council for Education and Training in Social Work in Scotland, and David Lane, who was director of social services in Wakefield, West Yorkshire, England.

Proceedings will begin at Banbridge courthouse with an opening address from Sir Anthony.

Former intelligence officer Brian Gemmell has said that MI5 forced him to cut short his investigation into the home in 1975

Barrister and junior counsel to the inquiry Joseph Aiken, will then provide a detailed overview of the Kincora Boys' Home before witness evidence is heard over the next three to four weeks.

In 1981, three senior care workers at Kincora were jailed for abusing boys – one of whom, William McGrath, was believed to have been an MI5 agent.

Campaigners had hoped to have Kincora included in the nationwide child abuse probe chaired by New Zealand judge Lowell Goddard because the HIA does not have the power to compel witnesses.

However a legal challenge to overturn the Government's refusal was rejected as “premature” by a High Court judge last month.

An appeal was also turned down.

The HIA is now in its 15th module and by the time it concludes public evidence sessions this summer, more than 450 witnesses will have provided oral testimony.

Sir Anthony is expected to submit his findings to MLAs at Stormont by early next year.