The Metropolitan police is looking into allegations that Tottenham Hotspur put the board of the Olympic Park Legacy Company (OPLC) under surveillance.

Baroness Ford, chairman of the OPLC, which is in charge of securing a viable economic future for the home of the London 2012 Games, told the London Assembly: "The thing that I have learned in the last 12 months is that there has been all kinds of behaviour. 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 that 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."

Scotland Yard confirmed on Tuesday that the investigation into the surveillance claims are "very much active". A spokesman said: "We can confirm that West Ham Football Club and the Olympic Park Legacy Company have made allegations to the Metropolitan police service in respect of the unlawful obtaining of personal information.

"These allegations have been assessed and an investigation has now commenced by officers from the economic and specialist crime command."

Later in the day, a 29-year-old man was arrested on suspicion of fraud following the allegations. He was arrested at an address in Sussex and was taken into custody at a Sussex police station "where he remains", a spokesman said.

"As part of their inquiries, detectives have conducted searches at both a residential and business premises in Sussex, a second private address in Sutton, and a further business address in Westminster," police said. "An amount of material was seized during the searches."

A deal with West Ham and Newham council to use the stadium in Stratford, east London after the 2012 Games, collapsed last month amid legal challenges, with the Government announcing that the stadium would remain in public ownership. Tottenham had already lost out to West Ham in the race to become the OPLC's first choice to move into the stadium after the Games.

Legal challenges by Tottenham and Leyton Orient, plus an anonymous complaint to the European Commission, had led to fears that court action could drag on for years while the stadium remained empty.

A new tender process is being launched by the OPLC and the showpiece venue, complete with an athletics track, will now remain in public ownership and be rented out to an anchor tenant.

Spurs rejected Ford's accusations, 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."

Baroness Ford told the London Assembly's economy, culture and sport committee: "I am expecting the unexpected because that is what the last 12 months has taught me. Our job now is to narrow as far as we possibly can the scope now for legitimate legal challenge in this next process – that is all that we can do.

"If people want then to be vexatious, frivolous and vindictive or whatever they want – they will do that."

The ECS committee chairman Dee Doocey said: "I personally find it appalling, and I am sure I speak for the rest of the committee, at the very idea of your board being put under surveillance is reprehensible.

"It almost beggars belief that this thing can happen. The idea that any board can be put under surveillance is absolutely disgraceful."