The family of one of the Bloody Sunday victims yesterday accused the British government of suppressing documents about former prime minister Sir Edward Heath's knowledge of the killings.
However, Mr Christopher Clarke QC, counsel to the inquiry, described the suppression claim as "most unfair".
Lord Gifford QC and Mr Richard Harvey, representing the family of James Wray at the Bloody Sunday Inquiry, believe the cabinet office has suppressed documents which throw light on Sir Edward's alleged "planning and foreknowledge" of Bloody Sunday.
Documents, including ministerial briefings and notes of the Northern Ireland Cabinet Committees chaired by Sir Edward in 1972, are missing, the legal team claimed in a written submission to the inquiry.
These documents shed light on the motives and knowledge of the leading players and the cabinet office should appear before the inquiry to explain, it was claimed.
Sir Edward, 86, was the conservative prime minister on January 30th, 1972 when British paratroopers shot dead 13 unarmed men on a Londonderry civil rights march.
He had been due to give evidence to the inquiry today but, following a fall outside Salisbury Cathedral on Sunday, he will now give evidence in the New Year.
The most likely explanation for the papers being withheld is that "their contents are embarrassing for the interests of the government", the submission claims.
The Wray legal team believes the government has frustrated the search for contemporaneous documents even though prime minister Tony Blair ordered this fresh investigation in 1998.
Inquiry staff have been diligent in seeking these documents but "these efforts are being thwarted by a refusal on the part of the present government to disclose what they still possess", the submission states.
It points out that no briefings have been disclosed for the crucial meetings in January 1972 when decisions were taken about the Londonderry march, including an unscheduled meeting between Sir Edward and Northern Ireland prime minister Brian Faulkner on January 27th, 1972.
Records of telephone conversations between both leaders for January 1972 have not been disclosed although those for 1971 have been released.
Missing documents which are seen as having special importance are those relating to the Northern Ireland Cabinet Committee meetings held on January 27th and 31st. The first meeting would contain insight on the discussion of the military plans for the march, it was claimed.
The team also wants to see notes of the meetings between Sir Edward and Mr Faulkner on January 27th and February 4th.
The Wray family lawyers also point out that Sir Arthur Hockaday, who was then the adviser on Northern Ireland in the cabinet office, has confirmed that he would have drafted the briefing of these meetings and they would have been held in the Public Records Office.
Counsel for the inquiry, Mr Clarke told the hearing: "I have no present reason to believe the cabinet office has deliberately suppressed documents." On November 4th some of the briefing notes had been delivered among batches of other relevant documents but had not been available for circulation because they were being examined, he said.