A 29-year-old man was arrested on suspicion of fraud on Tuesday following allegations Tottenham spied on officials during their Olympic Stadium bid.
The arrest came as Baroness Ford, chairwoman of the Olympic Park Legacy Company (OPLC), charged with securing the stadium's future post-Games, claimed all 14 members of her board were watched.
"The thing that I have learned in the last 12 months is that there has been all kinds of behaviour," Baroness Ford said. "There has been legal challenges and people have stood behind it anonymously - all kinds of things have happened.
"My board were put under surveillance by Tottenham Hotspur and the chairman of Tottenham Hotspur felt confident enough to say in the Sunday Times several months ago that all 14 members of my board were put under surveillance. The Metropolitan Police are now conducting an investigation into that surveillance.
"There has been all kinds of behaviour here that I could not have anticipated which, believe me, has not been pleasant in the last 12 months.''
Tottenham have denied the allegations, releasing a statement saying: "The club did not undertake, instruct or engage any party to conduct surveillance on any member of the OPLC committee and we consider the making of this baseless accusation to be wholly inappropriate and irresponsible. We totally reject the accusation in the strongest possible terms.''
Detectives, who have been investigating claims since August 2011, said the suspect was arrested at an address in Sussex. The probe was launched after allegations "in respect of the unlawful obtaining of information'' were made by OPLC and West Ham.
West Ham defeated Tottenham in a bid to use the arena after the Games - but the Hammers' deal collapsed, and the stadium will remain in public ownership.