Some 3,000 Olympics tickets from international sports federations were "put back in the pot" on Sunday night and sold to the public, Locog has said.
The move came after the sights of swathes of empty seats at events in the first days of the Games prompted anger from people who had struggled to get tickets.
London 2012 chairman Sebastian Coe had promised to urge international federations to make sure they used areas reserved for them to avoid embarrassment.
Jackie Brock-Doyle, Locog's director of communications, said they had been able to get back 3,000 and re-sell them - a move they will do each day to make sure as many seats as possible are filled.
"We talked to the International Federations yesterday, we were able to put back into the pot for sale around 3,000 tickets last night, they have all been sold," she said. "That includes about 600 for the gymnastics event today and we're going to do that on a day-to-day basis."
She said they were talking to accredited groups, including broadcast media and seeing if they can release some tickets. Ms Brock-Doyle said the number of seats given up depended on the sport, and in some situations also depended on security arrangements, but in those cases, they had contingency plans involving giving seats to troops or students and teachers.
Asked if they had "got it wrong", she said: "We are trying everything we can to make sure that those accredited seats are filled where we can. There are operational issues that make it difficult to fill some of those seats which is why we are making them available to the troops and to the teachers and the children."
Shadow Olympics minister Dame Tessa Jowell, who held the post in 2005 when Britain won the right to hold the Games, has demanded urgent action to end the issue. She said: "We've got to get people into those seats today, tomorrow and the next day. I think the measures Seb Coe announced yesterday go quite a long way into that, together with the recycling of tickets for people who are already in the park. This is very important for the confidence of the British public."
Culture Secretary Jeremy Hunt told BBC Radio 4's The World At One a possible 30-minute rule was being considered.
He said: "Well that's what we're looking at doing. We're looking at whether we are able to do it, but we are hosting this event under a contractual arrangement that we have with the International Olympic Committee and sports federations and so we do have to respect what we've agreed to contractually in order to get London to host the Games."