The former owner of Manston Airport has been told by MPs to put her deal with the new owners into the public domain to counter claims of asset stripping.
The Kent airport closed last May, seven months after being bought by Ann Gloag, co-founder of the Stagecoach Group.
She subsequently sold a majority stake of the 700-acre site to regeneration specialists for redevelopment.
The Commons Transport Select Committee said Mrs Gloag should make clear who would benefit from any redevelopment.
A spokeswoman for Mrs Gloag said she would not be commenting on the MPs’ report into smaller airports, which follows evidence given to the select committee in February.
Campaigners fighting to keep the airport open petitioned Thanet District Council following its closure asking it to compulsorily purchase the site.
In December, the council considered a compulsory purchase order (CPO) involving US investment firm RiverOak as the indemnity partner, but decided not to proceed with it.
However, in the select committee report, MPs said Kent County Council (KCC) should have done more to support Thanet as it considered the CPO.
They said KCC had failed to fulfil its “strategic oversight function as the local transport authority”.
KCC has not yet commented on the report.
Earlier this month, a government review was ordered into the decision not to go ahead with the CPO.
The committee concluded that although welcoming the decision, “the uncertainty faced by the public and other interested parties could have been reduced if it had not taken three months before the Department for Transport acted”.
It added that there “is no general case for the government to purchase airports like Manston”.