Fairfax County has cut off negotiations with a developer to convert a Reston park-and-ride lot into a mix of dwellings, shops and offices around aplanned Metrorail station, officials said, citing a failure to reach an agreement over financing.

The county had sought a public-private partnership to redevelop its nine-acre site on Wiehle Avenue, the last stop in the first 11.6-mile phase of the extension of Metro to Dulles.