The Chief Constable faced questions at the Policing Board following the publication of the Operation Kenova report into the agent Stakeknife.

Pressure is growing on the Government to name Stakeknife after the publication of the final report from Operation Kenova.

It also details how the Army’s agent in the IRA was handed tens of thousands of pounds.

Moira Todd’s brother Eugene Simons was disappeared by Stakeknife’s unit in the Provisional IRA in 1981.

Vincent Kearney complained to the Investigatory Powers Tribunal.

The review was carried out after the material was discovered last year.

The police ombudsman for Northern Ireland investigated a claim made in a manuscript allegedly authored by a former military officer.

Kenova chief Sir Iain Livingstone has written to Northern Ireland Secretary of State Hilary Benn raising his concern at the late disclosure.

Former Taoiseach Bertie Ahern called on the UK intelligence services to release all information about the 1974 attacks

MI5 raised the threat level about a year ago

A severe threat means an attack is highly likely, while a substantial threat means one is considered likely.

The four were reported to the PPS for consideration across six files submitted by Operation Kenova investigators.

Stakeknife worked within the IRA’s notorious “nutting squad”, interrogating suspected informers during the Troubles.