By Tim Donovan
Political Editor, BBC London
Hooliganism during West Ham United's matches at London's former Olympic stadium has cost the taxpayer more than £500,000 this year.
The figures were revealed by the London Legacy Development Corporation (LLDC), which manages what is now called London Stadium, as well as the Queen Elizabeth Olympic Park.
The LLDC's Lyn Garner said police and stewards had to be deployed because of the bad behaviour of fans.
The comments were made during a London Assembly committee meeting.
Ms Garner, head of the LLDC, said that although dealing with rowdy supporters had cost more than £500,000, West Ham United were not required to pay for the extra costs.