Archery fans have been duped into buying fake tickets for the first London-based action of the Olympics.
Dozens of people turned up to the men's archery ranking round at Lord's cricket ground to find out that their tickets were counterfeits.
The disappointed fans were denied entry to the event, which is traditionally held behind closed doors.
A London 2012 spokeswoman confirmed that "a few" people arrived at the site with fake tickets.
It is understood that others believed the event was non-ticketed and that they could gain access free of charge.
Several people had queued from early in the morning in the hope of gaining access on a "first come, first served" basis and numbers peaked at around 50 by the time the archers had started shooting.
The London 2012 spokeswoman said: "Tickets have not been advertised or sold by Locog for the archery ranking event which starts today at Lord's cricket ground. We have always made it clear that the preliminary rounds are not open for spectators.
"There are a number of unofficial websites claiming to sell tickets; we therefore advise people to be extremely cautious and vigilant when attempting to buy tickets and only purchase from an official source - if in doubt there is a url checker on our website which will identify official sources."
Meanwhile, three people who were due to work as security staff at an Olympic venue were arrested on suspicion of immigration offences, the Home Office said.
The trio were drafted in to work as security guards at St James' Park, Newcastle, but were arrested on Wednesday - just 24 hours before the Mexico and South Korea match at the stadium. The three were employed by a private security firm, but were not G4S staff, a Home Office spokesman said.