Two MI5 agents whose evidence may throw light on Mr Martin McGuinness's movements on Bloody Sunday will have to give live testimony to the Saville inquiry.
They are being called because they worked with a former IRA informant who claimed that Sinn Féins' Mr McGuinness, now MP for Mid Ulster, fired the first shot on the march on January 30th, 1972, when British paratroopers killed 13 men.
The inquiry has rejected an application by the security services for a time-delay restriction to be imposed when the agents, identified only as Officers A and B, take the stand.
The rejected application also included former MI5 agent Mr David Shayler, an inquiry spokesman confirmed.
Officer A acted as a handler for the informant, codenamed "Infliction", and Officer B debriefed him.
Lord Saville, the inquiry chairman, had previously ruled that Infliction would not have to give evidence because it would put his life at risk and breach his human rights.
Infliction is alleged to have told this handlers that he heard Mr McGuinness confess to firing the first shot. Mr McGuinness has admitted being the IRA's number two in Derry on Bloody Sunday but insists he did not fire shots.
PA