A former British military intelligence officer has claimed that several British governments have always known that Sinn Féin's Mr Martin McGuinness did not open fire in Derry on Bloody Sunday, despite a claim by an agent known as "Infliction" that Mr McGuinness had fired the opening shot from a Thompson sub-machine gun which precipitated the Bloody Sunday killings.
The inquiry was also told that British Defence Secretary Mr Geoff Hoon believes that if the former military intelligence officer's identity became known, he could be murdered.
It was alleged by "Infliction" that Mr McGuinness, who was second in command of the Provisional IRA in Derry on Bloody Sunday, told him he fired the first shot as paratroopers were deployed into the Bogside.
However, a former military intelligence officer, codenamed Martin Ingram, has told the inquiry in his submitted statement that he had seen "hundreds" of intelligence documents relating to Bloody Sunday, none of which supported "Infliction's" allegation.
The former intelligence officer, who was also a soldier and a member of the top-secret Force Research Unit, said that according to the documents, Mr McGuinness was the subject of constant surveillance on Bloody Sunday.
He also said that the documents recorded that according to intelligence received prior to the demonstration, there was no intention from either the Official or Provisional IRA to undertake military activity on Bloody Sunday.
Martin Ingram further claims that the files show that no shots were fired at the paratroopers prior to them opening fire on unarmed civilians.
The former intelligence officer, who is due to give evidence to the inquiry next month, has asked to do so from behind a screen to protect his identity.
His application has been supported by Mr Hoon, who has told the inquiry that if Martin Ingram's real identity became known, terrorists would be "keen to interrogate, torture and murder him".
Martin Ingram's barrister, Mr David Waters QC, said his primary application on behalf of his client was for him to be screened when he gives his evidence on May 12th.
"May I start by reminding the tribunal that in his statement of July 27th, Mr Ingram said that he is anxious that the inquiry should be given full and complete information to enable it to examine and report on the events of Bloody Sunday, so that justice can be seen to be done for all those concerned.
"That is his primary stance," he said.
However, opposing the application, Mr McGuinness's barrister, Mr Peter Cush, said the issue was one of natural justice and fairness.
He claimed that the "organs of the state" had put every obstacle in the way of Mr McGuinness.
The inquiry's chairman, Lord Saville of Newdigate, said the inquiry's three judges would rule on the matter at the earliest possible opportunity.
The inquiry was adjourned until today.