Sinn Fein's head of administration of Stormont, Denis Donaldson, has been charged with possessing documents likely to be useful to terrorists.
They are understood to include the personal details of the senior British army officer in Northern Ireland, Lt Gen Sir Alistair Irwin.
Donaldson was remanded in custody until October 11 after pleading not guilt to the charges.
More than 200 Sinn Fein supporters, many holding placards staged a protest outside the court.
The banners included one accusing the police service of Northern Ireland of doing the work of Ulster Unionist leader David Trimble.
The crowd, which included women and children, remained peaceful throughout the protest.
Gerry Adams, flanked by members of his Assembly team, criticised Secretary of State John Reid for cancelling a meeting with his party.
On his way into the courtroom, he said: "What is he afraid of? Our party have no questions to answer on these matters.
"I am sure that in the fullness of time, when all the dust settles down, that Denis Donaldson will walk free. I am also very, very certain that when the spin and the political theatre is finished, this process is going to have to be put together again, and we as a party are going to be needed to do that."
Mr Adams added said that the Sinn Fein head of administration had been "hung, drawn and quartered" by media reports.