West Ham have denied claims from the London Legacy Development Corporation that they do not have the power to veto a groundshare at the Olympic Stadium.

The LLDC finance executive, Geraldine Murphy, told an information tribunal that a groundshare could happen “if the teams co-operate and the Premier League co-operates”, during its appeal hearing against the disclosure of West Ham’s tenancy agreement at the Olympic Stadium.

In 2014 Karren Brady, the West Ham vice-chairman, said: “No one has asked us for our permission [to groundshare] and, if they did, we would probably say no.” Murphy said West Ham did not have a veto on such a decision, even if it would require the co-operation of the east-London club. However, a statement from West Ham said they have “overriding priority” to use the stadium.

“As anchor tenant we have primacy of use during the football season and our contract gives us overriding priority to use the stadium, ensuring our fixtures and events are ring-fenced and will always take priority over all other events. It would therefore be impossible to accommodate the fixtures of another Premier League club without West Ham agreeing, a position which was fully supported at today’s hearing.”

It is understood West Ham are not ruling out a ground share but say they would have the final decision on any agreement. Tottenham and Chelsea are looking for temporary homes for when White Hart Lane and Stamford Bridge undergo redevelopment. However, both clubs are attempting to strike a deal at Wembley.

A coalition of 14 supporters’ trusts was represented at the tribunal on Monday, with the LLDC arguing a freedom of information request regarding West Ham’s tenancy agreement at the Olympic Stadium should be rejected, as it would prejudice future commercial negotiations.

West Ham will move into their 54,000-capacity ground next season and in September 2015 the Information Commissioner ordered their tenancy contract to be published without redactions. West Ham’s annual rent, thought to be £2.5m, has never been confirmed while details of catering, hospitality and naming rights agreements have also never been disclosed.

Richard Hunt, who made the original FOI request, said outside the hearing: “I think among football fans it’s more or less a universal concern. You’d be hard pushed to find anybody who would argue in defence of the deal. Football fans have crossed tribal lines to work together on an issue like this, it’s a testimony to the other guys that we have been able to work collaboratively as a team.”

A three-person panel headed by the tribunal judge, Melanie Carter, heard arguments from Murphy as to why the tenancy details should remain private. She argued it would affect commercial negotiations and, ultimately, impact negatively on the taxpayer.

West Ham, who were not represented at the tribunal between LLDC and the Information Commissioner, have agreed a 99-year lease and paid £15m towards the £272m conversion costs needed to transform the stadium into a dual-purpose venue for football and athletics.

“It’s a very competitive market,” said Murphy. “Competitors will use the release of this agreement to undercut commercial deals. It would benchmark negotiations at a point. In any commercial negotiation, it’s very difficult if you’ve got an anchor.”