An official at the Food and Drug Administration overruled front-line agency scientists and approved the sale of an imaging device for breast cancer after receiving a phone call from a Connecticut congressman, according to internal agency documents.

The legislator’s call and its effect on what is supposed to be a science-based approval process is only one of many of accusations in a trove of documents regarding disputes within the agency’s office of device evaluation.

Nine agency scientists complained in May to Andrew C. von Eschenbach, the F.D.A. commissioner, and the agency began an internal review. Dissatisfied with the pace and results of that review, the scientists wrote a letter to Congress in October pleading for an investigation, and the House Committee on Energy and Commerce announced in November that it would begin one. Last week, the scientists wrote a similar letter to President-elect Barack Obama’s transition team.

Agency documents that are part of the internal investigation, including e-mail messages, were provided to The New York Times. Details of the investigations have not previously been made public.