A blunder led to more than 400 tickets being wrongly allocated for Northern Ireland's opening Euro 2016 game, a Stormont committee has heard.
The "inadvertent error" by Uefa meant tickets were issued to applicants who were not considered priority supporters.
But there was some good news yesterday after it emerged the Irish Football Association had secured 600 additional tickets.
An extra 505 will be made available for the Ukraine match, with 93 added for the fixture against world champions Germany.
IFA officials have vowed they will keep pressing for more in the coming weeks. It will go some way to appeasing fans left furious over the fiasco surrounding tickets for this summer's finals in France.
Hundreds of supporters reacted with anger after finding out they would miss Northern Ireland's first game in a major tournament for 30 years.
Some who followed the team for two decades failed to get tickets for the June 12 opener against Poland, yet others who had never attended a Northern Ireland match were successful.
The controversy reached Stormont yesterday as IFA officials appeared before the culture, arts and leisure committee.
Chief executive Patrick Nelson revealed 428 tickets were wrongly given out for the Poland game. People who the IFA believed "had almost no priority at all" were successful, he told MLAs.
He blamed the shambles on a "very small, inadvertent error" by Uefa. He explained 2,100 tickets were available at category three level - the second-cheapest option - for the opening game against the Poles.
The IFA asked Uefa to allocate one-third of these to an option (Follow My Team) that allowed fans to attend all Northern Ireland's Euro 2016 games in and beyond the group stage, should they qualify. The rest were to be allocated to individual requests.
Mr Nelson said Uefa did the opposite, and put too many tickets into the FMT option.
"Uefa inadvertently over-supplied the Follow My Team bucket for category three tickets to the Poland game," he explained.
"They put more tickets into that particular bucket than we had advised them to."
He said Uefa was contacted at "the highest level" and within hours almost 1,000 tickets were allocated to Northern Ireland for the Poland game. A further 437 tickets were made available last Friday.
Mr Nelson also revealed 505 further tickets had been added for Ukraine in Lyon on June 16 and 93 more for Germany in Paris five days later.
"In terms of where we started ... we are 35% up on the Poland game, we're 20% up on Ukraine and we're 20% up on Germany," he said.
"But we'll carry on having conversations with Uefa as they get around to allocating more tickets."
Mr Nelson said Uefa had been left in no doubt of the IFA's determination over the issue. "If we can get more tickets we absolutely will," he said.
"I think (Uefa) will be much more aware now of who they're dealing with at the Irish Football Association. They will know that we won't lie down... we will fight the corner for our supporters."
UUP MLA Leslie Cree raised concerns about supporters being charged over the odds by touts.
The Belfast Telegraph reported last week how tickets for the Ukraine fixture were being sold online at up to £2,500 each.
He asked what protection was in place to stop the black market trade. Mr Nelson said tickets would have the buyer's name printed on them.
"There will be a very high degree of security around the games," he added. "I think Uefa are doing as much as they can to ensure that black marketeers don't profit from this."
DUP MLA David Hilditch questioned if Uefa had a security system to trace tickets.
Heather Wright of he IFA said tickets had not been dispatched. She said Uefa's legal team can be notified of any Northern Ireland tickets currently on sale.
"If they can trace who they correspond to, those tickets won't be issued at all," Ms Wright added.
Yesterday's meeting also heard that disabled fans had missed out on tickets because of a separate blunder. Ms Wright said they were part of the same priority system, but some were denied tickets because Uefa did not recognise their 'blue badges'.