Unsuccessful London 2012 ticket applicants have been able to buy tickets on a first-come-first-served basis from this morning - but the ticket website has struggled to cope with the demand.
Organisers say the website is working, but users have complained of crashes and being unable to complete purchases.
Around 2.3 million remaining tickets went on sale at 6am and will be available to buy for the next 10 days.
Events such as archery, basketball, fencing, judo, synchronised swimming and table tennis are included in the available tickets.
But many visitors hoping to purchase tickets this morning received a message reading: "We are experiencing high demand.
"You will be automatically directed to the page requested as soon as it becomes available. Thank you for your patience."
Organisers denied the website had crashed this morning.
A London 2012 spokeswoman said: "The system is working, it has not crashed. Due to high demand some people are being held outside the system.
"For those in the system it is working and transactions are going through, but we are having to hold some people back from going through the site due to high demand."
The system began to slow just 10 minutes after the second round of sales opened this morning. But organisers compared the situation to trains being held back before a Tube station because of a high amount of traffic in the station at the time.
Organisers say the website is working, but users have complained of crashes and being unable to complete purchases.
Around 2.3 million remaining tickets went on sale at 6am and will be available to buy for the next 10 days.
Events such as archery, basketball, fencing, judo, synchronised swimming and table tennis are included in the available tickets.
But many visitors hoping to purchase tickets this morning received a message reading: "We are experiencing high demand.
"You will be automatically directed to the page requested as soon as it becomes available. Thank you for your patience."
Organisers denied the website had crashed this morning.
A London 2012 spokeswoman said: "The system is working, it has not crashed. Due to high demand some people are being held outside the system.
"For those in the system it is working and transactions are going through, but we are having to hold some people back from going through the site due to high demand."
The system began to slow just 10 minutes after the second round of sales opened this morning. But organisers compared the situation to trains being held back before a Tube station because of a high amount of traffic in the station at the time.
