The chairman of the London Legacy Development Corporation has defended the secrecy around West Ham’s Olympic Stadium deal, claiming disclosing the information could cost “hundreds of millions” in the future.

Addressing the London Assembly’s plenary committee, David Goldstone said: “We feel we have to balance the obligations to be transparent, which we take very seriously, with the need to protect tens or hundreds of millions of value.”

The stadium, in Queen Elizabeth Olympic Park, is undergoing a £272million transformation ahead of West Ham becoming the anchor tenant in the summer.

It has been controversial ever since the move was announced in 2011, with some perceiving the Hammers to be getting a new stadium on the cheap.

During the meeting on Wednesday, assembly member Stephen Knight raised concerns about the lack of transparency around the West Ham deal and the challenging of the information commissioner’s ruling.

The Liberal Democrat asked whether the board’s position in using public money to appeal the ruling had changed.

David Edmonds, the LLDC’s chairman, confirmed it had not, adding: “We believe there is a real risk to rather larger sums to the public purse were this particular set of data to be given.”

Mr Knight said that West Ham were only contributing around £15m of the £272m conversion cost and would pay a yearly rent of between £2m and £2.5m – “a lot less than other Premiership clubs are paying for their grounds”.

“In effect, one could argue they are getting the ground really at a public subsidy,” he said.

Mr Goldstone defended this, saying: “The comparison with other clubs is difficult because this deal is unusual.

“This isn’t West Ham’s stadium. The stadium has remained in public ownership, we own it effectively with a joint venture with the London Borough of Newham, and West Ham get to use it on a set number of days each year and the rest of the time it can be used for other activities.

“All the revenue from those activities, as is clear from the agreement that we’ve released, will come through to ourselves and not to benefit West Ham.

“The important thing is we’ve got a deal that makes the stadium sustainable long term.”