The UK Government has said it is prepared to disclose all relevant material surrounding Northern Ireland's past conflict to an independent Historical Investigations Unit (HIU).

The HIU is among a suite of organisations planned to investigate the bloody legacy of the Troubles once differences with nationalists over what critics claim is the state's national security "veto" are resolved.

It was envisaged in political agreements, which have been stalled ahead of implementation amid the dispute.

Some families of more than 3,200 murder victims believe national security concerns could be used to prevent release of information held in official files. The Irish Government has said those harmed during the 30-year Troubles have been let down by the lack of progress.

A UK Government statement said: "This Government is committed to full and faithful implementation of the Stormont House Agreement, including the establishment of the new institutions to address the legacy of the past."

It said the administration will continue to engage with victims' groups, political parties and the Stormont Executive to build the necessary political consensus to get the Stormont House political agreement legacy institutions up and running.

"However, success or failure does not rest on the UK Government alone," said the statement. "It will not hinge on a national security 'veto' which is a simplistic characterisation failing to recognise that the UK Government has agreed to disclose all relevant material it holds to the HIU."

Institutions agreed following political talks between the British and Irish Governments and the local parties included the HIU, an independent body tasked with investigating large numbers of outstanding criminal cases connected to the Troubles and stretching back decades.

The Irish Coalition Government has said it "deeply regretted" the lack of visible progress on establishing institutions to deal with the fall-out from the violence.

The UK Government has differences with nationalists over how to balance the need of families to find new information about how their loved ones died and the hopes of some for prosecutions with the official responsibility to protect national security and prevent further loss of life.

Funding to support dozens of inquests into past killings has been withheld amid Stormont divisions, principally between the DUP and Sinn Fein. The UK Government said: "Of course, the Executive and Northern Ireland's political parties must play their part too.

"Detailed work continues to establish new bodies that command support and confidence, as we seek to build a Northern Ireland that works for everyone."

ends