Following the Commission's statement that it intends to make planning a core part of its inquiry, Lidl has lodged a complaint with the OFT.
Lidl said a site that it had identified in Fort William, Scotland, was the only feasible location for a supermarket in the area.
However, although the present tenant was willing to sign over the lease, Morrisons, had a covenant with the local council, inherited from Safeway, that barred direct competitors from using land neighbouring its store.
Morrisons said: "This was an agreement fully entered into by the council and Safeway. We see no reason to vary it."
A Lidl spokesman added: "Our advisors confirm that the restriction contravenes the Competition Act 1998."