Organizers LOCOG announce that more Olympic tickets will go back on sale after the row over empty seats.
It said an initial 3,000 tickets – including 600 gymnastics tickets – were “put back into the pot” and sold on the London 2012 website on Sunday night.
More tickets returned by sports federations would be released the night before events, LOCOG added.
Transport chiefs say London’s morning rush hour went well on the first full working day of the Games.
Prime Minister David Cameron, meanwhile, said the empty seats were “disappointing” but not “a unique episode” with other previous Games facing similar problems.
At some venues, seats in the accredited “Olympic family” areas – reserved for groups including officials, sports federations, athletes, journalists and sponsors – have remained empty.
LOCOG communications director Jackie Brock-Doyle said organizers were doing everything they could to fix the problem.
“We’re doing this session by session, talking to the accredited groups – including obviously broadcast media and everybody else – and asking whether we can release, for the different sessions, tickets back into the public pot,” she said.
And she said accredited seating for London 2012 was down 15% on previous Games.
Lord Sebastian Coe – who has said Olympics venues are “stuffed” with sports fans – had earlier said that some empty seats would be filled by servicemen and women, as well as local students and teachers.
And shadow home secretary Yvette Cooper said unused tickets should also be given to police officers and their families.