The Northern Ireland Office has denied claims that child sex abuse allegations are being treated "less seriously" here than the rest of the UK.
The statement comes after two key witnesses due to testify at the Historical Institutional Abuse (HIA) Inquiry - which is investigating abuse at the notorious Kincora boys' home during the Troubles - said they will now not give evidence.
In 1981, three senior care staff at the east Belfast home were jailed for abusing 11 boys, but allegations of a wider paedophile ring with links to the political and security establishment have persisted ever since.
Unionist commentator Roy Garland and former Army intelligence officer Colin Wallace said the Banbridge inquiry chaired by Sir Anthony Hart has not been given adequate powers to get to the truth.
Both men were disappointed by a recent High Court ruling that barred a judicial review of a government decision not to refer Kincora to the more powerful London-based Goddard Inquiry.
In a statement the NIO said: "He (Sir Anthony) has full legal powers, backed up by criminal sanctions, to compel witnesses and require them to produce documents in Northern Ireland. If people refuse to co-operate with the Hart Inquiry, Sir Anthony will have the option to use those powers."
But rather than reassure him, Mr Garland said it merely confirmed his reasons for not attending, as key witnesses living in Great Britain will remain beyond Sir Anthony's reach. Nor does the local inquiry have the powers to compel the production of documents such as Home Office files held outside Northern Ireland.
However, the Westminster inquiry chaired by Justice Lowell Goddard does have those powers.
Mr Garland said: "They can't compel witnesses from outside Northern Ireland. The British people who were involved, in the security forces, are the crucial ones in terms of the involvement in British intelligence. This backs up what I said."
Despite this, the NIO said Sir Anthony is conducting a "rigorous and effective" inquiry and that it is confident he will conduct the "fullest possible" investigation.
The NIO said: "There are absolutely no grounds for any claims that the Government treats allegations of child sex abuse any less seriously in Northern Ireland than in the rest of the UK.
"The UK Government has been very clear that it, and all its departments and agencies, will provide full co-operation."