The war of words between West Ham United and their taxpayer-funded landlords escalated again on Monday when the London Stadium owners claimed they are now spending £70,000 extra per game because of the club's fans.

Sir Peter Hendy, the chairman of London Legacy Development Corporation, angrily denied the club's "extremely serious and damaging" allegations that his organisation had given misleading information about their financial agreement.

In an open letter to the London Assembly, Sir Peter said costs had gone up again since estimates last season that the LLDC was losing £2million a year as a result of the deal which allows West Ham use the ground for an annual rent of £2.675 million. "Since then costs have increased, not least because the behaviour of a small minority of West Ham fans at the end of last season means we now spend more on security," he wrote. "Each match so far this season costs an average of around £270,000 to stage."

West Ham responded furiously last week after Lyn Garner, the chief executive of LLDC, told the London Assembly: "The elephant in the room is the fee they pay us for usage costs does not cover the event-day costs." The club claimed the LLDC receives £10 million annually in rent and associated income. "West Ham United are concerned that this is deliberately misleading the public and, more importantly, taxpayers," the club said.