Troops, students and teachers could all be asked to fill gaps left in empty Olympic stadiums, Lord Coe said yesterday.
Members of the military were being brought in at the last minute, students and teachers from the local area were also being invited and other fans could have their tickets upgraded, organisers said.
Tickets for double sessions, such as those for hockey, basketball, water polo and handball, are also being recycled and re-sold as people leave.
Lord Coe said: "It's not easy to ask people (in the accredited Olympic family) at the beginning of the Games to ask people exactly how, where and when they're going to be in those seats.
"This morning was a very good example, we looked at gymnastics, we could see at this moment there are empty seats in the accredited area – the rest of the venue is looking pretty good this morning, there's a good atmosphere.
"So we were able to move those troops from – I'm not quite sure whether they were on a rest period or whether it was a transition from work through to a rest period – but they're sitting there enjoying the gymnastics.
"We can and we have moved them in there.
"Yesterday, we got pre-accredited students and teachers from the local boroughs. We were able to put 115, 120 into a venue."
The London 2012 chairman went on: "We can clearly sell more tickets, which we did yesterday. We sold something like 1,000 tickets over three sessions.
"The other thing is we can tactically upgrade and move people."
Asked about how other tickets would be recycled to others in the Olympic Park, he said: "It's very much on the Wimbledon format.
"It sensibly takes place in our park venues, where we've got classically the double headers, in sports like hockey, basketball water polo, handball.
"On handball yesterday, we recycled just under 300 tickets, about 283 tickets, and they went out to adults at £5 and children at £1.
"Those numbers will increase over the course of the Games.
"It's sensible. People who classically have gone to see one specific team, but the ticket covers them for the next session, and they leave to go to do something else."
Yesterday reporters said there were some large chunks of empty seats even at United States v France at the Basketball Arena, one of the top draws. Organisers reacted by using one block as a press box overspill, while some troops were invited in to take up more empty seats.
There were very few empty seats for the morning and afternoon sessions at the Water Polo Arena, but the section for the Olympic Family was half-empty for the morning sessions.
The boxing venue at ExCel, in terms of buyable tickets, was almost completely full.
At the tennis, the blocks of seats at Wimbledon reserved for those with accreditation showed the biggest gaps. The majority of the other seats were full, particularly the cheaper ones towards the back of the stands.
Great Britain's volleyball men started in front of a largely full house at Earls Court, although pockets of seats were left vacant. There were also unused seats in the delegation and media areas.
Wembley Arena, which has a capacity of 4,800 for the Games, has been officially sold out for the badminton. The hall has been close to full for the sessions held so far, with three rows unoccupied due to restricted view.