Harvard officials are still waiting for the State Secretary of Environmental Affairs to approve a final impact statement that would allow construction to begin on the $50-million Medical Area power plant.

Although Donald C. Moulton, assistant vice president for community affairs and Harvard coordinator for the project, said yesterday he expects the state to authorize construction soon, officials in the environmental office said yesterday that no immediate approval can be expected.

"Nothing's resolved," Raymond Galardi, an official in the environmental office, said yesterday. "Things are still up in the air."

Boston Edison officials re-affirmed yesterday that Edison intends to sue to stop construction of the power plant immediately after the state approves the project. Edison is the current electrical supplier for the medical-related institutions in the area.

Moulton, however, said he does not expect Edison will go through with court proceedings against the plant's construction.

Construction on the plant, which will provide electricity, steam, chilled water, and waste incineration to ten medical-related institutions in the Mission Hill area including the Harvard Med School, was originally set to begin this summer.

But community protests and the state's rejection of the draft copy of the environmental impact statement have delayed construction on the project.