The Bloody Sunday Inquiry was told yesterday that just 10 soldiers out of a total of hundreds who were on the streets of Derry on January 30th, 1972, have so far come forward.
Mr Christopher Clarke QC, counsel for the inquiry, said the tribunal had "very little information about the present whereabouts of the soldiers involved".
Mr Clarke said the British Ministry of Defence (MoD) had supplied the tribunal with the last known addresses of 103 soldiers involved in the events of Bloody Sunday, but he understood some of the addresses were 20 years out of date.
It also emerged at the hearing that two soldiers, thought previously by the tribunal to be dead, may still be alive.
The chairman of the inquiry, Lord Saville, asked counsel for the MoD, Mr Ian Burnett QC, why the MoD's efforts to trace all the soldiers involved had "largely been a failure".
Lord Saville said the inquiry would now have to employ staff to try to locate the soldiers and were starting an exercise in July which could have been started in April (when the inquiry formally opened).
Mr Burnett said the task of tracing the soldiers was not easy as records were not held together. Great efforts had been made by the MoD. He said there were no comprehensive lists of all those serving at the time and that it was not "as simple as going to a filing cabinet and pulling out a file".
Mr Burnett said under the Data Protection Act, the names and addresses of those soldiers currently receiving army pensions could not be provided.
Lord Saville said the tribunal would contact the government agency handling army pensions and ask for letters to be sent to the soldiers asking them to give their names and addresses voluntarily.
Mr Edwin Glasgow QC, representing the soldiers, said 10 men had so far come forward to the MoD looking for legal representation. They had been referred to him, but his team "had not thought it right to go looking for clients".
He said they would take whatever steps the tribunal deemed appropriate.
Mr Glasgow said his team had had a "a Chinese wall, an information barrier erected around us because we saw from the outset a potential conflict of interest between the soldiers and everyone else".
He undertook to inform the tribunal if or when he was asked to represent any other soldier.
Mr Clarke also outlined other problems faced by the tribunal. He said "a large amount of documentary material" held by the firm of solicitors acting for the relatives of the victims, Madden and Finucane, had not been handed over.
Mr Clarke said the tribunal had however received a substantial amount of material - 30,000 pages of documentation and more than 1,000 photographs. The process of getting documentary evidence had been "more time consuming than we would have wished", he said.
The question of immunity from prosecution for witnesses was also discussed at yesterday's preliminary hearing.
No such applications have yet been received, but counsel for the soldiers said because it was not sought in his initial submission did not mean such immunity would not be requested in the future.
Lord Saville said no decision had been taken on this yet, but if people thought their words could be held against them, they would be much less likely to be of help. "Our task is to try to find the truth," he said.
The question of whether evidence given at the tribunal could be used in subsequent prosecutions will be discussed when the hearing resumes today.