The Government has pledged to respond to a major investigation into a top Army agent within the Provisional IRA after it makes its final report.

Operation Kenova probed the activities of the agent known as Stakeknife, who was part of the Provisional IRA’s notorious internal security unit (ISU) which was involved in abductions, torture and murder during the Troubles.

The interim report of the investigation concluded that more lives were probably lost than saved through the operation of Stakeknife.

It also calls on the UK and the IRA to apologise to bereaved families and victims of the ISU; the security forces for failings amid a “maverick” culture for handling agents and intelligence; and the IRA for the abduction, murder and torture of people it suspected of being agents, and linked campaigns of intimidation against their families.

Responding, Northern Ireland Secretary Chris Heaton-Harris said the Government could not comment on the detail of the report until the final version was published.

He paid tribute to the work of Kenova, saying it had gained the trust of many victims’ families seeking answers about what happened to their loved ones.

“As this is an ‘interim’ report, I will not comment at this time on behalf of the Government on the detail of the report. It contains several specific, very serious allegations that remain subject to consideration by the courts,” the minister said.

“It would not be right for the Government to make any comment on the substance of the interim report until the conclusion of litigation related to it.

“I note the recent decisions made by the Public Prosecution Service for Northern Ireland in relation to files passed to them by Operation Kenova, which once again go to show how difficult it is to achieve criminal justice outcomes in legacy cases.

“Due to numerous related civil cases, however, that remain ongoing, it would be inappropriate to comment further at this time.

“There is also the prospect of appeals against any of the recent decisions made by the Director for Public Prosecutions for Northern Ireland.”

Mr Heaton-Harris added: “I would like to put on record again my deepest sympathy with all the families who lost loved ones during the Troubles – including as a result of the actions of the Provisional IRA.”

Meanwhile Downing Street said it would not comment on the report published by Operation Kenova until the inquiry had completed its work.

A Number 10 spokeswoman said: “We would want to extend our deepest sympathies with all the families who lost loved ones during this very dark period in Northern Ireland and it’s important we do not forget the thousands of victims, their families and neighbours from all communities who have suffered as a result.

“On this interim report, it would not be right to comment on the substance of it while it is an interim report.

“We will respond in full in due course following the full and final report and also following the conclusion of litigation which is related to the substance of this report.”